MATERIAL WORLD. Working Document

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1 MATERIAL WORLD Page!47!

2 PoL: Material World A. 3.d.iv MATERIAL WORLD Properties of Solutions: Concentration I understand and would be able to determine the concentration of an aqueous solution in g L, percentage or ppm Explanation of Concept(s): Concentration is a measurement of the amount of solute dissolved in a certain amount of solution. Various units can be used to express concentration. They include: - g L: grams of solute per litre of solution - %( (m V): grams of solute per 100mL of solution - %( (V V): ml of solute per 100mL of solution - %( (m m): grams of solute per 100g of solution - ppm : 1 mg of solute per 1L of solution Some basic conversions: 1 L = 1000 ml 1 kg = 1000 g 1 g = 1000 mg In order to make a more concentrated solution, more solute must be added or less solvent can be used Page!48!

3 Multiple Choice Questions g of CaCl 2 is transferred to a 500mL volumetric flask and water is added until the 500mL line. Determine the concentration of the solution in ppm. a) 0.08 ppm b) 8 ppm c) 80 ppm d) 800 ppm Constructed Response Question 2. A laboratory technician needs to prepare 450mL of a 15 % (m v) NaCl solution. What amount of solute will be required? 3. The following solutions were found in a school laboratory. Jason was asked to organize them in ascending order of concentration. What should the final order be: 5 g L 4 % (m v) 200 ppm 2g 100mL 4. Calcium ions are found in bottled water, if the concentration of Ca 2+ ions found on the bottle label reads 100 ppm, represent this concentration in terms of g L. Answers 1. c 2. 15g 100mL = xg 450mL, x= 67.5g of NaCl ppm (0.2 g L), 5 g L, 2g 100mL (20 g L), 4 % (m v)) (40 g L) g L Page!49!

4 PoL: Material World A. 3.e.i Properties of Solutions: Electrolyte I understand and would be able to describe the concept of an electrolyte. Explanation of Concept(s): An electrolyte is a substance that can conduct an electric current when it is dissolved in water. Substances that are electrolytes include, acids, bases and salts. They will only conduct electricity if dissolved in water because when they dissolve in water, they dissociate into ions. For example, when the acid HCl dissolves in water, the following dissociation reaction results: HCl (aq) H + (aq) + Cl - (aq) The ions are charged particles. If electrodes(connected to a battery) are placed in this HCl solution, the positively charged particles(h + ) travel to the negative electrode and the negatively charged particles(cl - ) travel to the positive electrode, thus allowing current to flow. As shown above, acids dissociate to release H + ions. In general, bases dissociate releasing hydroxide(oh - ) ions. For example, Mg(OH) 2(aq) Mg 2+ (aq) + 2 OH - (aq) When a salt is dissolved in water, it separates into its component metal and non-metal ions: For example: CaCl 2 Ca 2+ (aq) + 2 Cl - (aq) Here is an example of a salt containing a polyatomic ion that dissociates when added to water: BaSO 4(aq) Ba 2+ (aq) + SO 4 2- (aq) Compounds that do not conduct electricity are called non-electrolytes because they do not dissociate into ions. They include sugars like glucose (C 6 H 12 O 6 ) and alcohols like methanol (CH 3 OH). Page!50!

5 Multiple Choice Questions 1. Substance A was found in a laboratory, various tests were performed on it in order to classify it. The following was observed: substance A had no effect on litmus paper, was able to conduct electricity and turned cobalt chloride paper pink. This substance can be classified as a) an acid b) a base c) an electrolyte d) a non-electrolyte Constructed Response Question 2. What conditions must be met for a substance to be called an electrolyte? Answers 1. C 2. Acid, base, or salt dissolved in water and producing positive / negative ions Page!51!

6 PoL: Material World A. 3.g.i Properties of Solutions: ph Scale I understand and would be able to describe the ph scale( acidity, alkalinity, neutrality, increasing and decreasing values, logarithmic nature of the scale) Explanation of Concept(s): The ph scale is used to measure how acidic or basic a substance is. The ph scale rages from 0 to being the most acidic and 14 being the most basic. A solution with a ph below 7 is acidic. A solution with a ph above 7 is alkaline (basic). A solution with a ph equal to 7 is neutral. The ph scale is a logarithmic scale meaning every increment of ph, is equivalent to a 10 fold decrease in acidity. For example a solution with a ph of 2 is ten times more acidic than a solution with a ph of 3, and 100 times more acidic than a solution with a ph of 4. ph Scale X 10 ACID BASE Page!52!

7 Multiple Choice Questions 1. A solution with a ph that is greater than 7 and less than 14 is: a) acidic b) alkaline c) neutral d) salty 2. An increasing ph means that : i) H + are decreasing ii) H + are increasing iii) OH - are decreasing iv) OH - are increasing a) i, b) ii c) i, iv d) ii, iii Constructed Response Question 1. In the lab, a technician finds a solution with a ph of 8, however, he needs a solution that is 1000 times more basic than that. He needs to find a solution with a ph equal to? Answers 1. b 2. c 3. Every ph increment of one is a 10 fold increase in basicity therefore the ph = 11 Page!53!

8 PoL: MW A. 3.g.ii Properties of Soutions: phscale I would be able to determine the ph of a few common substances(e.g. distilled water, rainwater, saliva, lemon juice and cleaners) Explanation of Concept(s): The ph ranges from 0 to 14. Here are the ph values of a few common substances: ph substance 1.0 battery acid 2.0 lemon juice 2.2 vinegar 3.0 apples 4.5 tomatoes, normal rain 6.6 milk 7.0 pure water 7.4 human blood 8.3 baking soda 10.5 milk of magnesia 14.0 sodium hydroxide ph values taken from: ph Nutrition Guide to Acid/Alkaline Balance) Page!54!

9 Multiple Choice Questions 1. Determine which of the following choices describe substances with a ph below 7 i) vinegar ii) ammonia cleaner iii) seawater iv) soft drinks v) tomato juice a) i, ii, iii b) ii, iii c) i, iv d) i,iv,v Constructed Response Question 2. Place the following substances in increasing order of ph: Distilled water Soap Lemon juice Rainwater Answers 1. D 2. lemon juice(ph 2), rainwater(ph 5), distilled water(ph 7), soap (ph 10) Page!55!

10 PoL: Material World A. 3.i.i Properties of Solutions: Ions I understand and can describe the concept of an ion. Explanation of Concept(s): An atom is neutral. It has an equal number of protons and electrons. The number of protons a neutral atom has is dictated by its atomic number. An ion is an atom that has either lost or gained one or more electrons. Metals tend to lose electrons to become positively charged ions. Non-metals tend to gain electrons to become negatively charged ions. Electrons are lost or gained in order for the ion to end up with a full octet of electrons which is 8 electrons (this is known as the octet rule). A metal like sodium (Na), is found in group 1 of the periodic table, it has 1 valence electron, therefore it loses 1 electron when it ionizes to become Na 1+. The neutral Na atom has 11 protons and 11 electrons. When it ionizes to become Na 1+, it ends up with 11 protons and 10 electrons, for a net +1 charge. (IA) (IIA) (IIIA) (IVA) (VA) (VIA) (VIIA) (VIIIA) Group Gain or lose e- Net charge lose 1e- lose 2e- lose 3e- lose or gain 4e- gain 3e- gain 2e- gain 1e- does not gain or lose e / Example Na + Mg 2+ Al 3+ CH 4 N 3- S 2- Cl - Ne Multiple Choice Questions 1. Choose the correctly symbolized ion from among the following: a) S 2+ b) S 2- c) Mg 2- d) F 1+ Page!56!

11 2. The Symbol for beryllium ion is: a) B b) Be c) Be 2+ d) Be 2- Constructed Response Question 3. Determine the ion that results when the following elements are ionized. a) Cl b) Li c) Ar d) C e) N Answers 1. b 2. c 3. a) Cl - b) Li + c) Ar d) C 4+ and C 4- e) N 3- Page!57!

12 PoL: Material World A. 3.j.i Properties of Solutions: Electrical Conductivity I understand, can interpret and describe the mechanism that allows aqueous solutions to conduct electricity(electrolytic dissolution of a solute, formation of mobile ions) Explanation of Concept(s): An ionic substance placed in water will dissociate into its ions. For example, sulfuric acid, H 2 SO 4 will dissociate as follows: H 2 SO 4 (aq) 2 H + (aq) + SO 4 2- (aq) When electrodes(connected to a battery) are placed in an electrolytic solution like H 2 SO 4, the positively charged particles(h + ) travel to the negative electrode and the negatively charged particles(so 4 2- ) travel to the positive electrode, thus allowing current to flow. Multiple Choice Questions 1. Which of the following substances will conduct electricity: i) Alcohol ii) Aqueous KCl iii) NaCl in its solid form iv) Sugar solution A. ii B. ii, iii C. ii, iv D. i, ii, iv Constructed Response Question 2. You find a container in your school lab with KCl crystals based on its molecular formula; you conclude that it is a salt. You test for its electrical conductivity, and surprisingly find that it does not conduct electricity. How can this be explained? 3. What process must occur in order for the salt sodium chloride to conduct electricity? Answers 1. a 2. KCl must be dissolved in water in order for it to dissociate into its ions(k +, Cl - ) 3. NaCl must first be dissolved in water so that it can separate into its ions; sodium ions(na + ) & chloride ions( Cl - ). The Na + ions can now travel to the negative electrode and the Cl ions are free to travel to the positive electrode so the current is able to flow Page!58!

13 PoL: Material World B.3.e.i Chemical Changes: Combustion I understand, can interpret and describe the recognizable manifestations of rapid combustion. E.g. Heat, light, Fuel Explanation of Concept: Combustion is a form of oxidation (uses oxygen) that releases a large amount of energy. Rapid Combustion: Within a short period of time, fuel can burn and release a great deal of energy mostly in the form of heat and light. E.g. A candle burning. Multiple Choice Questions: 1. Which of the following is NOT example of rapid combustion: a) A log fire b) Candle Burning c) Digestion d) Gas stove Short Answer: 1. Rusting is considered to be slow combustion whereas starting a campfire is rapid combustion. Explain why a campfire is an example of rapid combustion? Answers: Multiple Choice: 1. C Short Answer: Rapid combustion occurs when fuel is burned which results in the release of large amounts of energy. In the example of a campfire, the wood logs are releasing large amounts of heat and light which classifies this as rapid combustion Page!59!

14 PoL: Material World B.3.e.ii Chemical Changes: Combustion I would be able to explain a combustion reaction using the fire triangle. Explanation of Concept: Combustion is a form of oxidation (uses oxygen) that releases a large amount of energy. Three conditions must be met for combustion to occur: 1. Oxidizing Agent: Is something that can cause fuel to react like oxygen. 2. Ignition Temperature: is the minimum temperature at which there is enough energy to start the combustion. This varies from one type of fuel to another. 3. Fuel: is a substance that releases a large amount of energy by reacting with an oxidizing agent. (E.g.: Wood) Combustion will continue to occur until one of the three factors is significantly reduced or no longer present in the situation. E.g. Heat is significantly reduced by water cooling it down. Rapid Combustion: Within a short period of time, fuel can burn and release a great deal of energy mostly in the form of heat and light. E.g. A candle burning Questions: Short Answer: 1. A friend shows you three conclusions he arrived at after doing her research on forest fires: 1) If the wind increases, the forest fire will also increase. 2) Forest fires are more common in summer, when it is hot and dry, than in autumn, when it is cold and wet. 3) Forest fires are more likely to occur in mature forests than in young forests. Explain each of the conclusions by using the fire triangle. Page!60!

15 2. Each year, forest fires reduce a significant area of land in Quebec to cinders. Sometimes these fires are the results of human activity but most often, they are caused by lightning strikes. The environmental impact of this natural phenomenon, which is part of the life cycle of the Boreal Forests, is often widespread. In July 2005, the smoke produced by a gigantic forest fire in northern Quebec darkened the skies as far south as the Montreal region. Using the terms below, explain how forest fires affect the atmosphere. Illustrate your answer with a diagram and/or chemical equations. Combustion Respiration Photosynthesis The Carbon Cycle Oxygen Carbon Dioxide Answers: Short Answer: 1. If the wind increases the fire as the potential to be spread. Strong winds will push the flames in the direction the wind is blowing and can cause the surrounding woods to catch fire thus causing the fire to spread. Also, more oxygen in the air feeds fire. This is an example of an increase in the OXIDIZER. The hot summer months bring about a lot of sun. The sun s warmth can dry out the trees making the dry wood more prone to being ignited. Also, the sun itself can trigger fire especially after long periods without rain. This is an example of IGNITION TEMPERATURE. Mature forests are more prone to fire because there is more FUEL to be burned. More trees means more burning options more to burn. 2. Fires are a large contributor to the carbon cycle. The carbon that is in the structure of the plants being burned are being combusted using oxygen and producing high quantities of carbon dioxide. This is how Carbon returns to the atmosphere. As a result this carbon dioxide is now available for plants to use as they undergo photosynthesis. They use the carbon dioxide, water and the sun s energy to make their own food. As a result plants will grow which provides a source of food for animals. Animals will consume these plants as part of their respiration process which involves breathing oxygen, eating plants for example and drinking water. As a result animals are consuming carbon through the plants they eat and are releasing carbon in the form of gas every time they exhale. It is remarkable how intertwined everything is in our ecosystem. Page!61!

16 PoL: Material World B.3.f Chemical Changes: Photosynthesis and Respiration I would be able to represent the photosynthesis reaction in a balanced equation. Explanation of Concept: Plants and animals have a mutualistic relationship. They need each other for survival. Plants need to use elements of the world around them to make their own food. They use carbon dioxide, water and solar energy to undergo photosynthesis, a chemical change, that produces glucose stored in the plant s body and oxygen. The photosynthesis reaction can be represented by the balanced chemical equation below. 6CO 2(g) + 6H 2 O (l) + energy C 6 H 12 O 6(s) + 6 O 2(g) (Carbon Dioxide) + (Water) + solar energy = (Glucose) + (Oxygen) Translated, this means that 6 molecules of carbon dioxide chemical combines with 6 molecules of water in the presence of solar energy to produce 1 molecule of glucose and 6 molecules of oxygen. Page!62!

17 Multiple Choice Questions: 1. Which of the following combinations correctly explains the chemical equation and circumstances for photosynthesis? a) Carbon Dioxide + Water + solar energy = Glucose + Oxygen b) Carbon Dioxide + Water = Glucose + Oxygen + solar energy c) Glucose + Oxygen = Carbon Dioxide + Water + energy d) Glucose + Oxygen + energy = Carbon Dioxide + Water Short Answer: 2. Trees in a forest obtain energy through the process of photosynthesis. Using the following components, represent the photosynthesis reaction in a balanced chemical equation. Solar Energy 6O 2 6CO 2 6H 2 O C 6 H 12 O 6 a) Equation: b) Explain how this chemical reaction provides energy to the plants Answers: Multiple Choice: 1. A Short Answer: 2. Equation: 6CO 2(g) + 6H 2O (l) + energy C 6H 12O 6(s) + 6 O 2(g) (Carbon Dioxide) + (Water) + solar energy = (Glucose) + (Oxygen) Carbon Dioxide gas is taken in by the leaves of the plants and chemically combined with water taken in from the plants roots. Under solar energy the plant undergoes photosynthesis which is the process by which it makes its own food. Food gives the plant the ability to grow. Page!63!

18 PoL: Material World B.3.f Chemical Changes: Photosynthesis and Respiration I would be able to represent the respiration reaction in a balanced equation. Explanation of Concept: Animals and plants have a mutualistic relationship. They need each other for survival. Animals need to consume and burn energy. As a result they undergo respiration which involves the burning of glucose which has been consumed through eating with oxygen that has been inhaled. Cells will burn this fuel and give off waste in the form of Carbon Dioxide, water and energy. This respiration reaction can be represented by the balanced chemical equation below. C 6 H 12 O 6(s) + 6 O 2(g) 6CO 2(g) + 6H 2 O (l) + energy (Glucose) + (Oxygen) = (Carbon Dioxide) + (Water) + energy Translated, this means that 1 molecule of sugar combines with 6 molecules of oxygen and chemically changes through combustion into 6 molecules of carbon dioxide, 6 molecules of water and energy is released. Page!64!

19 Multiple Choice Questions: 1. Which of the following combinations correctly explains the chemical equation and circumstances for cellular respiration? a) Carbon Dioxide + Water + solar energy = Glucose + Oxygen b) Carbon Dioxide + Water = Glucose + Oxygen + solar energy c) Glucose + Oxygen = Carbon Dioxide + Water + energy d) Glucose + Oxygen + energy = Carbon Dioxide + Water Short Answer: 1. Animals obtain their energy from consuming energy. Using the following components, represent the cellular respiration reaction in a balanced chemical equation. energy 6O 2 6CO 2 6H 2 O C 6 H 12 O 6 a) Equation: b) Explain how this chemical reaction provides energy to the animal. Answers: Multiple Choice: 1. C Short Answer: 1. C 6H 12O 6(s) + 6 O 2(g) 6CO 2(g) + 6H 2O (l) + energy Glucose) + (Oxygen) = (Carbon Dioxide) + (Water) + energy As an animal eats glucose in either plant form or indirectly through meat, and inhales oxygen a chemical change takes place that results in the production of carbon dioxide, water and energy in the form of heat and muscular energy being given off as products. Page!65!

20 PoL: Material World B.3.g.i Chemical Changes: Acid-Base Neutralization Reaction I would be able to give examples of acid-base neutralization reactions (e.g. adding lime to neutralize the acidity of a lake) Explanation of Concept: Neutralization is a chemical reaction in which an acid combines with a base to form a salt and water. Acids release hydrogen ions (H+ ions), bases release hydroxide ions (OH- ions). When the number of H+ and OH- ions are equal then the result is a neutral substance (ph = 7) Page!66!

21 Multiple Choice Questions: 1. Wasp stings are alkali, which substance would help this injury a) vinegar b) toothpaste c) tap water d) ammonia based window cleaner Short Answer: ML of a solution with a ph of 4 is mixed with an equal amount of a solution with a ph of 10. Describe the type of reaction that will occur Answers: 1. A 2. The type of reaction is an acid-base neutralization. The reaction of the two solutions would result with ph Page!67!

22 PoL: Material World B.3.g Chemical Changes: Acid-Base Neutralization Reaction I would be able to name the products (salt and water) formed during acidbase neutralization reactions. Explanation of Concept: Neutralization Reaction: ACID + BASE SALT + WATER Acid: Generally have an H in the front of the formula (e.g.: HCl not H 2 O = water) Can be used to neutralize bases Base: Generally have OH at the end of the formula (ex: NaOH) Can be used to neutralize acids Salt: A metal and a non-metal combine to form a salt Does not have a H in front or OH at the end of the formula When an acid and a base combine they neutralize each other forming a salt and water. Both salt and water have a ph is neutral. For example: H 2 SO 4 + 2NaOH Na 2 SO 4 + 2H 2 O. H 2 SO 4 is an acid because it starts with H NaOH is a base because it ends in OH Na 2 SO 4 is a salt because Na is a metal and S and O are nonmetals. Together this equals a salt. H 2 O is, of course, water. Page!68!

23 Multiple Choice Questions: 1. When an acid and a base combine together, what are the products produced? Short Answer: a) Acid and Salt b) Salt and Base c) Base and Water d) Salt and Water 1. Look at the equation below. Classify each of the products and reactants as an acid, base or salt. Ca(OH) 2 + H 2 CO > CaCO H 2 O Reactant and Product Identification Ca(OH) 2 H 2 CO 3 CaCO 3 H 2 O Justification Answers: Multiple Choice: 1. D Short Answer: Reactant and Product Identification Justification PoL: Material World B.3.g.iii Ca(OH) 2 Base Has OH at the end of the chemical formula which is indicative to a base. H 2CO 3 Acid Begins with H which is an indication it is an acid. CaCO 3 Salt Is made of a metal (Ca) and two non-metals (C and O) which means this is an ionic bond and a salt. H 2O Water Formula for water Page!69!

24 Chemical Changes: Acid-Base Neutralization Reaction I would be able to recognize an acid-base neutralization reaction from its equation Explanation of Concept: The positive ion of (H + ) with negative the acid combines the negative hydroxide (OH - ) ions to form water (H 2 O) as a product. The positive ion of the base combines with the negative ion of the acid to form a salt The hydroxide ion and hydrogen ion combine to form WATER (Na + + OH - ) + (H + + Cl - ) (Na + + Cl - ) + (H + + OH - ) SALT WATER The sodium ion and chlorine ion combine to form a SALT Page!70!

25 Multiple Choice Questions: 1. Which equation below correctly represents the balanced neutralization reaction of hydrochloric acid (HCl) and potassium hydroxide (KOH)? a. HCl + KOH Cl + H 2 0 b. HCl + KOH KO + H 2 l c. HCl + KOH KH + ClOH d. HCl + KOH KCl + H 2 0 Short Answer: 1. From the chemical reactions below, select the one that is a neutralization reaction, then explain why it is a neutralization reaction: a. CH 4 + 2O 2 CO 2 + 2H 2 O b. C 6 H 12 O 6 + O 2 CO 2 + H 2 O + energy c. HF + LiOH H 2 O + LiF 2. Sodium hydroxide (NaOH), a very strong base, spilled in a laboratory. In order to safely clean the spill, hydrochloric acid (HCl) is used to neutralize it. Write the balanced neutralization equation for this reaction. Answers: 1. D 2. HF + LiOH H 2O + LiF is the neutralization reaction. The acid (HF) and the base (LiOH) react to produce the salt (NaCl) and water (H 2O). 3. NaOH + HCl NaCl + H 2O PoL: Material World B.3.j.i Page!71!

26 Chemical Changes: Law of Conservation of Mass I understand, can interpret and describe the law of conservation of mass during a chemical reaction Explanation of Concept: Law of conservation of mass: in all chemical reactions the mass of reactants is equal to the mass of products. Ex: How much CO 2 is needed to completely react? CH 4 + O 2 CO 2 + H 2 O 8g + 32g = x +18g CH O 2 CO H 2 O 8g + 32g = x + 18g Answer: 22 g of CO 2 Multiple Choice Questions: 1. What mass of ammonia (NH 3 ) is expected to form when 6 g of hydrogen gas (H 2 ) combines with 28 g of nitrogen gas (N 2 )? a) 6 g b) 23 g c) 34 g d) 46 g N H 2 2 NH 3 Page!72!

27 Short Answer: 2. The neutralization of 2 g of hydrochloric acid (HCl) with 3.1 g of potassium hydroxide (KOH) produces 4.1 g of potassium chloride salt (KCl) and water. The balanced equation for this reaction is shown below: HCl + KOH KCl + H 2 O What is the mass of the water produced during this neutralization reaction? 3. When fossil fuels such as coal and oil are burned, sulfur is released into the atmosphere, and, as a result acid rain is formed. The following reaction takes place: SULFUR DIOXIDE + OXYGEN SULFUR TRIOXIDE SULFUR TRIOXIDE + WATER SULFURIC ACID (acid rain) If 260 g of sulfur dioxide react with 64 g of oxygen and the sulfur trioxide produced is further reacted with 80 g of water, how much sulfuric acid would is produced? Answers: 1. C 2. 2 g g = 4.1 g + water 5.1 g = 4.1 g + water 1 g = water g + 64 g = sulfur trioxide 324 g + 80 g = sulfuric acid 324 g = sulfur trioxide 404 g = sulfuric acid Page!73!

28 PoL: Material World B.3.j.ii Chemical Changes: Law of Conservation of Mass I would be able to represent the conservation of mass using the particle model Explanation of Concept: The particle model can be used to visually represent a chemical reaction. This can be applied to the law of conservation of mass to show an equal amount of reactants and an equal amount of products. Example: Using the symbols, show the reaction of the combustion of methane. CH O 2 CO H 2 O + + Page!74!

29 Questions Multiple Choice: 1. During a chemical reaction, one molecule of nitrogen gas (N 2 ) and three molecules of hydrogen gas (H 2 ) react to produce 2 molecules of ammonia (NH 3 ). The balanced equation for this reaction is: N H 2 2 NH 3 Below are some proposed models for each balanced equation. The following symbols are used. Nitrogen Hydrogen Page!75!

30 2. The following model represents a balanced equation for a reaction involving a piece of magnesium metal and hydrochloric acid. Symbols: Magnesium Hydrogen Chlorine Which of the following equations correctly represents this reaction? a. Mg + HCl H 2 + MgCl 2 b. Mg + H 2 Cl 2 H 2 + MgCl 2 c. Mg + 2 HCl 2 H 2 + MgCl 2 d. Mg + H 2 Cl 2 2 H MgCl 2 Short Answer: 3. The combustion of methane (CH 4 ), produces water (H 2 O) and carbon dioxide (CO 2 ) as shown in the equation below. CH 4 + O 2 H 2 O + CO 2 Using the symbols below create a model representing this balanced reaction. Symbols: Carbon Hydrogen Oxygen Answers: 1. D 2. C Page!76!

31 PoL: Material World B.3.k.i Chemical Changes: Balancing Chemical Equations I would be able to balance chemical equations Explanation of Concept: Balancing a chemical equation consists in placing a coefficient before each reactant and product so that the number of atoms of each element on the reactant side is equal to the number of atoms of each element on the product side. o Coefficients must be whole numbers placed in front of a reactant or product o Coefficients must be as small as possible (lowest common denominator) o New substances must never be added, nor existing substances removed o Subscripts in chemical formulas must never be changed o The final equation should always be checked by counting the number of atoms of each element on both sides Ex: Unbalanced H 2 SO 4 + KOH K 2 SO 4 + H 2 O Balanced H 2 SO KOH K 2 SO H 2 O Check balancing Reactants H: 2 + 2(1) = 4 S: 1 O: 4 + 2(1) = 6 K: 2(1) = 2 Products H: 2(2) = 4 S: 1 O: 4 + 2(1) = 6 K: 2 Unbalanced Balanced C 5 H 12 + O 2 CO 2 + H 2 O C 5 H O 2 5 CO H 2 O Check balancing Reactants C: 5 H: 12 O: 8(2) = 16 Products C: 5(1) = 5 H: 6(2) = 12 O: 5(2) + 6(1) = 16 Page!77!

32 Multiple Choice Questions : 1. Which of the following equations is balanced? a) 2Fe 2 O 3 + 3C 3CO 2 + 2Fe b) CH 4 + O 2 CO 2 + 2H 2 O c) Cu + 4HNO 3 Cu(NO 3 ) 2 + 4NO 2 + 2H 2 O d) 4NH 3 + 3O 2 2N 2 + 6H 2 O 2. Identify the missing substance in the following balanced equation: CaCO 3 + 2NaCl + CaCl 2 a) NaCO c) Na 2 CO 3 b) NaCO 3 d) 2NaCO 3 Short Answer: 3. Balance the following equations: a) KOH + H 2 SO 4 K 2 SO 4 + H 2 O b) CH 4 + O 2 CO 2 + H 2 O Answers 1. d) 2. c) 3. a) 2 KOH + H 2SO 4 K 2SO H 2O b) CH 4 + 2O 2 CO 2 + 2H 2O Page!78!

33 PoL: Material World C.1.g.i Organization of Matter: Groups and Periods in the Periodic Table I can locate the groups and periods in the periodic table Explanation of Concept: The periodic table of elements is an organization of the elements according to their physical and chemical properties. Groups: o Each column is called a group o The group number represents the number of valence electrons (electrons in the outermost shell). eg: Halogens are in group VII they all have 7 electrons in the outermost shell Periods: o Each row is called a period o The period number represents the number of shells or orbital eg: Period 3 elements, each have 3 shells of electrons. Page!79!

34 Multiple Choice Questions: 1. Which statement correctly locates these groups of elements: 1. alkali metals, 2. alkaline earth metals, 3. halogens, 4. noble gases i the column VIIIA ii. column VIIA iii. column IIA iv. column IA a) 1-i, 2-ii, 3-iii,4-iv, b) 1-iv,2-iii, 3-ii,4i c) 1-ii, 2iv,3ii,4iii d) 1iii, 2i,3iv,4ii 2. Which statement best describes the elements Be, O, F & Ne? a. They are all non-metals. b. They are all found in the second family. c. They have two valence electrons. d. They have electrons in two electron shells. Short Answer: 3. Two elements A and B have the following properties. Element A metallic luster two valence electrons twenty neutrons located in the 4 th period Element B without metallic luster six valence electrons eight neutrons has electrons on two shells Name the two elements. Answers: 1. B 2. D 3. Element A calcium Element B oxygen. Page!80!

35 PoL: Material World C.1.g.ii Organization of Matter: Groups and Periods in the Periodic Table I would be able to understand and describe the common characteristics of a group (e.g. number of valence electrons, chemical reactivity) Explanation of Concept: Alkali Metals (Group I): o Properties: Soft, light metals that melt at low temperatures Found combined with other elements (never found as free elements) Excellent conductors Highly reactive with water and air o Uses: Alkali metals are mostly used as compounds Sodium chloride (table salt) Sodium bicarbonate (baking soda) Lithium used to treat depression Sodium and potassium nitrates (fertilizers) Alkaline Earth Metals (Group II): o Properties: Grey, metallic solids that are excellent conductors Also reactive with air and water, but less vigorously than alkali metals Melting points are higher than alkali metals o Uses: Magnesium is used in fireworks and flash bulbs Calcium salts are used to melt ice on the road Barium sulfate is used in medical imaging (to image digestive system) Halogens (Group VII): o Properties: Nonmetallic properties These elements are very reactive (in nature they exist only in combined states diatomic) They form salts when combined with alkali metals They form strong acids in combination with Hydrogen They are toxic and corrosive o Uses: Iodine is essential to the proper functioning of the thyroid gland it s added to table salt (iodized table salt) Chlorine is used to disinfect drinking water (used in bleaching agents and some antiseptics) Fluorine (the most reactive) used for frosting glass Page!81!

36 Noble Gases or Inert Gases (Group VIII): o Properties: Lack of chemical reactivity as they have full outer shell of electrons Under ordinary conditions, they don t form compounds with other elements o Uses: Used to manufacture coloured light in illuminated signs (Ex. Neon lights) Helium is used to inflate balloons Argon is used to fill light bulbs and electronic flashbulbs Multiple Choice Questions: 1. A B C D An element is examined in the laboratory. Despite several attempts it doesn t seem to react with any other substance/compound. It is a gas at room temperature. Which letter best represents where this element would be located in the periodic table above Page!82!

37 Short Answer: 2. The properties of four elements are listed below. Element Property A It is a non-metal. It has seven valence electrons. B Its outermost energy level (orbit) contains two electrons. It has a metallic lustre. C It exists in the gaseous state. It does not react with other elements. D It has metallic lustre. It has 11 protons. It reacts violently with water. Given these properties, to which chemical group does each of these elements belong? 3. While doing a research project, you noted the following information about three elements. Element Properties Is a solid Conducts electricity A Has 2 electrons in its outermost shell Has a low density Has a very low density Does not conduct electricity B Has 7 electrons in its outermost shell Is light green in colour C Is found in very small quantities in nature Does not form compounds with other elements Is in a gaseous state Has a very low boiling point Identify the group for each element. Explain by giving at least two properties justifying your choice. Answers: 1. D 2. Element A Halogen Element B Alkaline Earth Metal Element C Noble Gas; Element D Alkali Metal 3. Element A Alkaline Earth Metal (reason: 2 electrons in its outermost shell, low density) Element B Halogen (reason: 7 electrons in its outermost shell, does t conduct electricity. Element C Noble Gas (reason: Does not form compounds with other elements, is in agaseous state Page!83!

38 PoL: Material World C.1.g.iii Organization of Matter: Groups and Periods in the Periodic Table I know that the number of electron shells in an element is the same as the number of its period Explanation of Concept: A period corresponds to a row of the periodic table. All the elements in a period have the same number of electron shells. Example: Multiple Choice Questions: 1. Which element below has the following properties? Has electrons in 2 electron shells Is a non-metal Is completely non-reactive or is inactive a. Li b. F c. He d. Ne Page!84!

39 Short Answer: 2. The periodic table is organized according to the properties of elements. The atomic structure of elements helps organize the elements in rows. Explain what Mg, Si, Cl have in common. Answers: 1. D 2. All elements in the third period and thus have the same number of electron shells (orbitals). Page!85!

40 PoL: Material World C.1.h Organization of Matter: Rutherford-Bohr Atomic Model I understand and can describe the Rutherford-Bohr atomic model. Explanation of Concept: Niels Bohr added to Ernest Rutherford s discovery of the atom by: 1) Conducting experiments using light that allowed him to conclude that the electrons of an atom exist on SPECIFIC energy levels which he called orbits. 2) These energy levels can also be referred to as rings, shells and orbitals. 3) The energy levels are what hold the electrons in their positions. 4) Electrons can move to other energy levels when stimulated by being heated or receiving an electrical discharge. 5) Therefore, the Rutherford-Bohr Atomic Model is a representation of the atom as a very small nucleus made up of positively charged protons, surrounded by negatively charged electrons moving in defined orbits (Observatory, p.15). Rutherford-Bohr Model Electrons are Negatively Charged (-) Chlorine Page!86!

41 Multiple Choice Question: 1. Which of the statements below does not explain the Rutherford-Bohr model? Short Answer: a) The number of protons and electrons are the same. b) The number of rings are indicated which correspond to the period number. c) The number of valence electrons is apparent which indicate the group number. d) The electrons are represented with positive charges. 2. The following diagram shows the Rutherford-Bohr model of an atom. Using the periodic table, answer the following questions: a) To what group does this element belong? b) To what period does this element belong? c) What is the name of this element? Answers: Multiple Choice: 1. D Short Answers: 1. a) Group 2 or Alkaline Earth Metals b) Period 3 c) Magnesium Page!87!

42 PoL: Material World C.1.h Organization of Matter: Rutherford-Bohr Atomic Model I would be able to represent atoms using the Rutherford-Bohr model. Explanation of Concept: To Represent the Rutherford-Bohr model: Locate the atom in the periodic table. The Atomic Number represents the number of protons (+) and electrons (-) the atom has. Indicate the number of protons in the nucleus of the atom. Do not forget to include the charge symbol. The period the atom is located in represents the number of energy levels it will have. Draw these energy levels. Indicate the number of electrons by drawing them on their respective energy levels and/or indicating how many there are per level by writing a number. DO not forget the charge symbol Remember: a maximum of 2e- on the first energy level, a maximum of 8e- on the second energy level, a maximum of 8e- on the third energy level and 2e- on the fourth energy level. You must fill up an energy level completely before placing electrons on the next level. Page!88!

43 Multiple Choice Question: 1. Which of the following correctly represents the atom using the Rutherford Bohr model? a) An atom with 6 protons, 2 electrons on the first shell and 4 on the second shell. b) An atom with 12 protons, 6 electrons on the first shell and 6 on the second shell. c) An atom with 19 protons, 2 electrons on the first shell, 8 electrons on the second shell and 9 electrons on the third shell. d) An atom with 2 protons, 1 electron on the first shell and 1 electron on the second shell. Short Answer: 1. The table below lists different elements. Choose two elements that are found in the same group in the periodic table and represent these atoms using the Rutherford-Bohr model. Name of Element Calcium Chlorine Iron Magnesium Phophorous Potassium Silicon Sodium Sulphur Chemical Symbol Ca Cl Fe Mg P K Si Na S Page!89!

44 Answers: Multiple Choice: 1. A Short Answer: Possible Answers: Calcium has 20 protons, 2 electrons on the first energy level, 8 electrons on the second energy level, 8 electrons on the third energy level and 2 electrons on the fourth energy level. and Magnesium has 12 protons, 2 electrons on the first energy level, 8 electrons on the second energy level and 2 electrons on the third energy level. OR Sodium has 11 protons, 2 electrons on the first energy level, 8 electrons on the second energy level and 1 electron on the third energy level. and Potassium has 19 protons, 2 electrons on the first energy level, 8 electrons on the second energy level, 8 electrons on the third energy level and 1 electron on the fourth energy level. Page!90!

45 PoL: Material World C.1.k Organization of Matter: Lewis Notation I would be able to determine the number of valence electrons in an element. Explanation of Concept: The number of valence electrons in an atom refers to the number of electrons located on the last energy level. Using the periodic table of elements one can easily determine the number of valence electrons by looking at the group number in Roman Numerals. Every element in the group will have the same number of valence electrons. For Example: All elements in Group II will have 2 electrons on their valence shell; they will have 2 Valence electrons. Page!91!

46 Questions: Multiple Choice: 1. Which of the following correctly matches the element with the number of valence electrons it possesses? a) Helium (2), Carbon (4), Magnesium (2), Potassium (1) b) Helium (8), Carbon (4), Magnesium (2), Potassium (1) c) Helium (1), Carbon (2), Magnesium (3), Potassium (4) d) Helium (2), Carbon (2), Magnesium (3), Potassium (4) Short Answer: 1. For each of the following elements indicate the number of valence electrons it possesses. Element Silicon Chlorine Argon Sodium Potassium Number of Valence Electrons Number of electron shells a) Which two of the above listed elements are in the same group? How do you know this? Page!92!

47 Answers: Multiple Choice: 1. A Short Answer: Element Number of Valence Electrons Number of electron shells Silicon 4 2 Chlorine 7 3 Argon 8 3 Sodium 1 3 Potassium 1 4 a) Sodium and Potassium because they have the same number of valence electrons. This means that these two elements will react in similar ways. Any element in the same group will have the same number of valence electrons and will share similar properties. Page!93!

48 PoL: Material World C.1.k Organization of Matter: Lewis Notation I would be able to represent atoms using Lewis notation. Explanation of Concept: Lewis Notation is a simplified way to represent the atom. It was designed to simplify the process of showing how atoms bond together (share electrons or give electrons). It is created by indicating the elements symbol followed by placing dots around the symbol corresponding to the number of valence electrons that atom has. The valence electrons are placed one by one around the symbol, like the points of a compass. When these four positions are filled, the electrons are then doubled to form pairs. You can start at any point on any side of the symbol. In addition, it does not matter which side is left empty when doubling up electrons. For Example: Chlorine has 7 valence electrons because it is in group VII of the periodic table. Therefore, 7 electrons need to be represented around the symbol for Chlorine which is Cl. The Lewis structure would therefore look like the image on the below. Questions: Short Answer: 1. The salinity of water is due to the presence of mineral salts. Sodium chloride (NaCl) is one of the salts dissolved in seawater. Using the periodic table, use Lewis notation to represent each atom that makes up sodium chloride (NaCl). Page!94!

49 Answers: Short Answer: Page!95!

50 PoL: Material World F.1.a.i Electricity and Electromagnetism: Electrical Charge I understand that different particles have different charges i.e. that a proton has a positive charge, a neutron has neutral (no) charge and an electron has a negative charge. Explanation of Concept(s): An atom is composed of small particles of matter: protons, neutrons and electrons. The following illustration represents the distribution of these elementary particles inside the atom: Figure 1: SUBATOMIC PARTICLES Electrical charge is a property of protons and electrons. It was proven that: - protons are positively charged (+); - electrons are negatively charged(-); Page!96!

51 Multiple Choice Questions 1) What do protons and electron have in common? A) They both carry an electrical charge. B) Neither of them carry an electrical charge. C) They are both situated outside the nucleus of an atom. D) They are both situated inside the nucleus of an atom. E). 2) Which of the following are positively charged? 1) The proton. 2) The electron. 3) The atom. 4) The nucleus A) 1 and 2 B) 2 and 3 C) 3 and 4 D) 1 and 4 3) Which of the following statements correctly describe a difference between electrons and protons? A) Protons are found outside the nucleus; electrons are found inside the nucleus. B) Protons are positively charged; electrons are negatively charged. C) Protons have no electrical charge; electrons have a positive charge. D) Protons are found inside the nucleus; electrons are found inside the neutrons Page!97!

52 Constructed Response Question 4) The concepts listed in the box below relate to the structure of an atom. Draw arrows to represent the correct match between each elementary particle, its location and its electrical charge: a) proton 1) inside the nucleus 2) outside the nucleus 3) negative charge 4) neutral b) electron 5) positive charge Answers Multiple Choices 1. a) 2. d) 3. b) Constructed Response Question: 1) a) proton 1) and 5) b) electron 2) and 3) Page!98!

53 PoL: Material World F.1.a.ii Electricity and Electromagnetism: Electrical Charge I understand that two objects with similar electrical charges will repel each other and that two objects with opposite electrical charges will attract each other. Explanation of Concept(s): Brought close together, two electrically charged objects interact: - when the charges are similar, the objects repel each other positive repels positive negative repels negative - when the charges are opposite, the objects attract each other positive and negative attract Page!99!

54 Questions MULTIPLE CHOICE 1) The list below arranges different substances in increasing order of their tendency to acquire electrons. When two of these substances are rubbed together, the one situated lower on the list attracts electrons from the substance above and becomes negatively charged. Table 1 ELECTROSTATIC SERIES CHART In the laboratory, a student rubs a cotton cloth with each of the following substances: ebonite, plastic, acetate and glass. He then brings different samples together: 1) ebonite and plastic 2) plastic and acetate 3) acetate and glass 4) glass and ebonite In which of the situations do the objects repel each other? A) 1 and 2 B) 1 and 3 C) 2 and 4 D) 3 and 4 Page!100!

55 2) Five metallic spheres were electrically charged and then suspended as shown in the diagram below: If sphere A lost electrons, which of the spheres were negatively charged? A) B and C B) C and D C) D and E D) B and E CONSTRUCTED RESPONSE 3. A student rubbed two identical inflated balloons on a piece of fur and suspended them from a high stand. He then rubbed a plastic ruler with a piece of wool and placed it between the two suspended balloons. The balloons quickly went high in the air as shown in the diagrams below. Knowing that the wool cloth transferred electrical charges to the ruler, determine the overall charge of the balloons, fur, ruler and wool cloth. Explain your answer. Page!101!

56 Answer 1 b 2 d 3. balloons fur ruler wool cloth Electrical Charge (positive/negative) negative positive negative positive Explanation The charges transferred from the wool to the balloons were electrons, because only electrons can move from one atom to another. The balloons acquired a surplus of electrons and became negatively charged. By transferring electrons to the balloons, the fur acquired a deficit of electrons and became positively charged. Since the ruler repels the two balloons, it must be negatively charged. By rubbing the ruler with the wool cloth, the ruler acquired electrons. The wool cloth has transferred electrons to the ruler so it acquired a deficit of electrons and became positively charged. Page!102!

57 PoL: Material World F.1.b.i Electricity and Electromagnetism: Static Electricity I understand and can describe static electricity as the transfer of electrons from one body to another. Explanation of Concept(s): An electrically neutral body contains the same amount of protons (positive charges) and electrons (negative charges). Protons are very tightly bound to the nucleus and cannot be easily removed. Some electrons however, are not so tightly bound and can be transferred from one body to another. These transfers usually occur when two bodies are rubbed against each other. The atom that loses electrons becomes positively charged. The atom that gains electrons becomes negatively charged. Figure 1: ELECTRICALLY CHARGED OBJECTS Electrical charges can also be transferred from one body to another by direct contact. Page!103!

58 Multiple choice Questions 1) Tom wants to prepare a surprise party for his baby sister. Amongst other things, he wants to decorate the walls of their house with multi-coloured balloons. Once the balloons are inflated, Tom rubs them on his hair for a few seconds and then sticks them to the wall. He knows that this is possible due to friction, as the balloons become electrically charged and are attracted to the wall. Which of the following produced the static electricity? F) The transfer of protons between the hair and the balloons. G) The transfer of electrons between the hair and the balloons. H) The transfer of electrons between the balloons and the wall. I) The transfer of protons between the balloons and the wall. 2) Among the statements below, find one that is TRUE. 5) Positively charged objects have a deficit of protons. 6) Positively charged objects have surplus of electrons. 7) Negatively charged objects have a surplus of electrons. 8) Negatively charged objects have a surplus of protons. 3) The following diagram shows four different objects and their electrical charge. The positive sign (+) represents the charge of the protons and negative sign (-) represents the charge of the electrons. Which of these objects are positively charged? A) 1 and 2 B) 2 and 3 C) 3 and 4 D) 1 and 4 Page!104!

59 Constructed Response Question 4. Demonstrations using ebonite rods and wool cloth are very common in static electricity activities. After being rubbed with wool, an ebonite rod attracts small objects. Ebonite is known to hold its electrons very tightly when rubbed against other substances. Wool on the other hand, exerts very weak attraction on its electrons. The diagram below shows the distribution of electrical charges before the two objects (ebonite rod and wool) are rubbed together: A) Show the distribution of electrical charges in the two substances after the two objects are rubbed together (use + and -). Explain your diagram. Explanation: B) Explain why the ebonite rod attracts small objects after being rubbed with the wool cloth. Page!105!

60 Answers Multiple choices 1. B; 2. C; 3.D; Constructed response question MW F.1.b.i 4. A. The wool cloth does not hold its electrons tightly, like the ebonite rod. By rubbing these substances together some electrons are transferred from the wool cloth to the ebonite rod. Before being rubbed, both objects contain equal numbers of positive and negative charges. After rubbing, the ebonite rod has a surplus of electrons whereas the wool cloth has a deficit of electrons. NOTE: The number of negative charges that are added to the ebonite should equal the number negative charges that were removed from the wool cloth. The number of positive charges remains the same in both objects, because the positive charges cannot be transferred. B. Since the ebonite has acquired a negative charge, when it is brought close to objects like small pieces of paper, Styrofoam etc, the positive charges in these objects will be attracted by the greater number of negative charges in the ebonite rod and will move towards it (get attracted to the ebonite rod). Page!106!

61 PoL: Material World F.1.c.i Electricity and Electromagnetism: Ohm s Law I understand and can explain the relationship between voltage, resistance and current intensity in an electrical circuit. Explanation of Concept(s) Ohm s law describes the relationship between several important physical quantities used in electricity. The current intensity (I) represents the amount of charge that flows through a point of an electrical circuit in one second. (Imagine the number of the cars (electrons) passing a point on a racetrack in one second.) The potential difference (V) is the amount of energy transferred by electrons between two points of an electrical circuit. (Imagine the amount of push needed to get a car on a racetrack from point A to point B.) The resistance (R) of an element or a circuit is a property of materials. It represents the ability of a material to oppose (resist) the flow of electric charges. (Imagine speed bumps slowing down the cars on a racetrack.) Ohm s Law states that: FOR A GIVEN RESISTANCE, THE POTENTIAL DIFFERENCE IN AN ELECTRICAL CIRCUIT IS DIRECTLY PROPORTIONAL TO THE CURRENT INTENSITY. MULTIPLE CHOICE QUESTIONS 1) In an electrical circuit, the number of electrons crossing through the section of a wire in one second has doubled. The total resistance of the circuit stayed the same. How did potential difference change? A) The potential difference halved. B) The potential difference doubled. C) The potential difference quadrupled. D) The potential difference stayed the same. Page!107!

62 2) What will happen to the current intensity in an electrical circuit if, for a given resistance the potential difference was reduced by half? A) It will double. B) It will not be modified. C) It will be reduced to half of the initial value. D) None of the above. CONSTRUCTED RESPONSE QUESTION 3) The resistance of a circuit is increased while the current intensity is maintained at the same value. A) How will the voltage vary? B) Explain why. ANSWERS 1. B 2. C 3. A) The voltage will increase. B) The resistance of an electrical circuit represents the capacity of a material to oppose the flow of electrical charges. As the current intensity and voltage are directly proportional, if the current is maintained constant and the resistance is increased, more energy will be needed for the current to flow through the resistor, so the voltage will increase. Page!108!

63 PoL: Material World F.1.c.ii Electricity and Electromagnetism: Ohm s Law I can use the equation (V = RI) to calculate voltage, resistance and current intensity in an electrical circuit (I can use Ohm s law in calculations) Explanation of Concept(s) The mathematical expression of Ohm s Law shows the direct proportionality between the potential difference and current intensity, for a given resistance: V=R I The above formula can be also written as: R= V/I and I = V/R Where: -V is the potential difference (voltage) expressed in volts (V) - I is the current intensity (current) expressed in amperes (A) - R is the resistance expressed in ohms (Ω) Questions In the circuit diagram below the voltmeter measures 12 V and the ammeter measures 0.6 A. 1. What is the resistance of element R? A) 0.05 Ω B) 7.2 Ω C) 20 Ω D) 7.2 J 2. What!is!the!potential!difference!of!a!current!of!10!A!flowing!through!a!resistance!of!25!Ω?! A) 250 Ω B)0.4 V C) 2.5 V D) 250 V Page!109!

64 3. You have a large flashlight that requires a 1.5 V battery. If the resistance of the light bulb is 3 Ω, what is the current flowing through the light bulb? A) 500 A B) 4.5 ma C) 2 A D) 4.5 A CONSTRUCTED RESPONSE QUESTION In the laboratory, a student was asked to measure different electricity parameters of an electrical circuit that needs 0.5 amps of current to function optimally. He has experimented with four different resistors and recorded the data in the table below. Table 2 RESISTANCE AND POTENTIAL DIFFERENCE VALUES Resistor Resistance (Ω) Potential difference (V) Perform the necessary calculations to show which of the resistors should be used for the optimal functioning of the circuit. ANSWERS 1 C 2 D 3 B 4 CONSTRUCTED RESPONSE QUESTION Resistor 1: Resistor 2:! =!! = 12!! 60!Ω = 0.2!!! =!! = 12!! 24!Ω = 0.5!! Resistor 3:! =!! = 12!! 48!Ω = 0.25!! Resistor 4:! =!! = 12!! 36!Ω = 0.3!! Answer: The resistor that should be used is RESISTOR 2 because IT PROVIDES THE OPTIMAL AMOUNT OF CURRENT FOR THIS CIRCUIT Page!110!

65 PoL: Material World F.1.d.i Electricity and Electromagnetism: Electrical Circuits I understand and can describe the function of different components of an electrical circuit (e.g. the wires transmit electrons along the circuit; resistors transform electrical energy into another form of energy) Explanation of Concept(s): Electrical circuits transform electrical energy into other forms of usable energy (light, heat, sound, mechanical energy etc). The table below presents some components of electrical circuits and their specific role. Table 3 BASIC ELECTRICAL CIRCUIT COMPONENTS AND THEIR FUNCTIONS COMPONENT power source, battery ELECTRICAL FUNCTION power supply DESCRIPTION creates a potential difference; transfers energy to electrons wires Conduction connect the elements and the power supply; carry electrons from the source to the elements and back to the source resistors(elements) electrical resistance limit the flow of electrons; transform electrical energy into other forms of energy (light, heat, sound etc) switch control allows the current control by connecting or breaking the circuit; (when a switch is off, the electron flow is interrupted) ammeter voltmeter measures the current flowing through a circuit (connected in series) measures the potential difference (energy) that electrons have between two points of the circuit (connected in parallel) Multiple Choice Questions Page!111!

66 1) In which of the following electrical circuits is the electron flow NOT possible? A) 1 and 2 B) 1 and 3 C) 2 and 3 D) 2 and 4 2) Which of the components depicted by the symbols below is used to STOP the electron flow in an electrical circuit? A) B) C) D) Page!112!

67 3) Which of the circuit components below is designed to hinder the flow of electrons through an electrical circuit? A) a copper wire B) an alkaline battery C) a light bulb D) an electrical switch Constructed Response Question 4) Draw arrows to match the components below with the right function they carry in electrical circuits: 1. converts electrical energy into other forms of energy 2. provides the energy to the circuit 3. controls the current 4. measures the current intensity 5. measures the voltage 6. carries the current 7. component that generates light a. ammeter b. resistor c. light bulb d. voltmeter e. power supply f. switch g. wires Answers Multiple choices: 1) D 2) D 3) C Constructed question: Page!113!

68 PoL: Material World F.1.d.ii Electricity and Electromagnetism: Electrical Circuits I would be able to identify the two main types of electrical circuits (series, parallel) Explanation of Concept(s): In an electrical circuit electrical charges flow continuously. In order for charges to flow, all parts of the circuit must be connected together. SERIES CIRCUITS In a series circuit, elements are linked directly together (connected end to end). All charges follow the same pathway. If a part of the circuit is open or an element is defective, the current ceases to flow through the entire circuit. Diagram 1: SERIES CIRCUIT Page!114!

69 PARALLEL CIRCUITS A parallel circuit branches out at least at one point (node). The charges follow different pathways. If a part of the circuit is open or an element is defective, the current continues to flow through the other branches. Diagram 2: PARALLEL CIRCUIT MEASURING INSTRUMENTS Ammeters are connected IN SERIES (the current passes through the ammeter). Voltmeters are connected IN PARALLEL (outside the element whose voltage is measured). Example: Diagram 3: MEASURING INSTRUMENTS Questions Page!115!

70 1) The diagram below shows a circuit made of two light bulbs, two switches and a power source. Which of the following statements regarding this circuit is TRUE? S 1 S 2 L 1 L 2 A) Opened Closed Off On B) Closed Opened On Off C) Opened Closed On Off D) Closed Opened Off On 2) Which of the circuits below are connected in parallel? A) 1 and 4 B) 2 and 4 C) 1 and 3 D) 2 and 3 Page!116!

71 Constructed Response Question: 3) In the circuit below, if S 1 is open and S 2 is closed, which lightbulb(s) will light up? ANSWERS 1- B 2- D 3 All three light bulbs will light Page!117!

72 PoL: Material World F.1.d.iii Electricity and Electromagnetism: Electrical Circuits I understand and can describe the differences between alternating and direct current Explanation of Concept(s): An electric current is an orderly flow of electrical charges. There are two types of electric current: DIRECT CURRENT (DC) - electrons continuously move in the same direction (ex. the current produced by a battery). Figure 1 MOTION OF ELECTRONS IN DIRECT CURRENT ALTERNATING CURRENT (AC) - electrons change direction many times every second (they flow back and forth); it is produced by power plants. Figure 2 MOTION OF ELECTRONS IN ALTERNATING CURRENT EXTRA INFORMATION Power plants produce alternating current. This is more advantageous as during the electrical current distribution, less energy is lost. Since most electrical appliances and electronic devices function on direct current, they usually use a regulator that transforms alternating current into direct current. Page!118!

73 Questions Multiple Choice Questions 1) Which of the following statements describe an alternating current (AC)? a) It is produced by a battery b) Electrons change direction continuously. c) The electrons and protons move in the opposite direction d) Electrons move in the same direction. Constructed Response Question: 2) The following diagram consists of two light bulbs connected to a D-cell battery. The circuit uses direct current. Use arrows to show electrons all along this the motion of circuit. ANSWERS Multiple Choices 1) B Constructed Response Question: ** All arrows must point in the same direction (negative to positive or positive to negative) Page!119!

74 PoL: Material World F.1.d.iv Electricity and Electromagnetism: Electrical Circuits I understand and would be able to represent a simple electrical circuit using a diagram and appropriate symbols. Explanation of Concept(s): A simple electrical circuit contains at least the following components: - a power source - resistors (elements) - wires Most circuits also contain one or more switches. In electricity, circuits are represented by precise diagrams. Certain symbols are used to represent the elements of an electrical circuit: Table 1 ELECRICAL CIRCUIT SYMBOLS wire power supply resistor light bulb switch ammeter voltmeter Page!120!

75 SERIES CIRCUIT The figure below represents a series circuit consisting of a power supply (electrical battery) and two resistors (light bulbs) along with its representation using symbols, in an electrical diagram: Figure 1: SERIES CIRCUIT circuit electrical diagram PARALLEL CIRCUIT The figure below represents a parallel circuit consisting of a power supply (electrical battery) and two resistors (light bulbs) along with its representation using symbols, in an electrical diagram: Figure 2: PARALLEL CIRCUIT circuit electrical diagram Page!121!

76 Multiple Choice Questions 4) The figure below represents a simple electrical circuit containing a power source, two electrical bulbs and one resistor: Which of the following diagrams could best represent this circuit? Page!122!

77 Constructed Response Questions: 5) The electrical circuit below contains two resistors, two light bulbs, a power supply and a switch - all connected by copper wires as shown in the figure below. Draw a diagram of this circuit using appropriate symbols used in electricity. Show the flow of charges on your diagram. 6) An electrical circuit is made of two resistors connected to a power supply, an ammeter and a voltmeter. In this circuit, all electrons follow the same pathway. The ammeter measures the current in both resistors whereas the voltmeter measures the potential difference of the first resistor only. Draw the circuit diagram, indicating also the measuring instruments. Page!123!

78 ANSWERS Multiple Choices 1) B 2) C Constructed Response Questions: 3) 4) Page!124!

79 PoL: Material World F.1.e.i Electricity and Electromagnetism: Relationship between Power and Electrical Energy I would be able to use the equation P= VI to calculate power, voltage and current intensity in an electrical circuit. Explanation of Concept(s): Electrical power is the amount of work an electrical device can perform in one second. The electrical power of a circuit is directly proportional to both voltage and current intensity and can be expressed in a formula as: P = V I Where: - P is the electrical power expressed in watts (W) - V is the voltage (potential difference) expressed in volts (V) - I is the current intensity expressed in amperes (A) Page!125!

80 Questions 1) A student was asked to assemble a simple electrical circuit made of a resistor and a battery and calculate its electrical power. Since he was asked to perform further calculations, he also connected a voltmeter and an ammeter to his circuit. The diagram below represents the circuit that he assembled: The current intensity in the circuit is 0.8 A and the voltage across the resistor is 20 V. What is the electrical power of this circuit? B) 0.04 W B) 16 kw C) 16 W D) 25 kw 2) What is the current drawn when a kettle with a power of 1.65 kw is connected to an 110V power supply? A) A B) 1.5 A C) 15 A D) 66.7 A 3) What is the voltage required by an electric grill with a power of 2.2 kw and current 20 A? A) 0.11 V B) 9.1 V C) 26.4 V D) 110 V Page!126!

81 Constructed Response Questions: 4) In the electrical circuit represented below, the voltage is 100 V and resistor R has a value of 50 Ω. Calculate the electrical power of resistor R. Show all your work. ANSWERS Multiple Choice 1) B 2) C 3) D Constructed Response Question: Example of an appropriate procedure: 1) Find current intensity:! = =! 2) Find electrical power: =! = = = Answer: the electrical power of the resistor is 200 W Page!127!

82 PoL: Material World F.1.e.ii Electricity and Electromagnetism: Relationship between Power and Electrical Energy I understand and would be able to explain, the relationship between the power of an electrical appliance, the electrical energy it consumes and the amount of time it is in operation. Explanation of Concept(s): The electrical energy consumed by an electrical appliance is directly proportional to the power of the appliance and the amount of time it is in operation. In other words, the more powerful an electrical appliance is, the more energy it consumes. The longer an appliance is in operation, the more energy it consumes. Page!128!

83 Questions 1) Which of the following would reduce the cost of using an electrical appliance? 1. Increase the operation time. 2. Use an appliance with a lower power rating. 3. Use a cheap appliance. 4. Reduce the operation time. 5. Use an appliance with a higher power rating. A) 1 and 3 B) 2 and 4 C) 3 and 5 D) 4 and 5 2. Lynn wants to buy a new hair dryer. The store sells two different models. The rating plates of the two appliances are shown below: She usually dries her hair for about 15 minutes daily and she would like to use the least amount of energy possible. Which of the two models should Lynn buy? Explain your answer ANSWERS Multiple Choice 1) B Constructed Response Questions: 2) Lynn should buy Model 1. The power rating of Model 2 is lower. Since the amount of energy consumed by an appliance is directly proportional to its electrical power, for the same amount of operating time this model is going to use less energy. Page!129!

84 PoL: Material World F.1.e.iii Electricity and Electromagnetism: Relationship between Power and Electrical Energy I would be able to use the equation E = PΔt to calculate the electrical energy consumed, the power of an electrical appliance and the amount of time it is in operation Explanation of Concepts The electrical energy of an electrical circuit can be calculated using the formula: E = P t Where: - E is the electrical energy expressed in joules (J) or kilowatt hour (kwh) - P is the electrical power expressed in W (watt) or kilowatt (kw) - Δt is the time interval expressed in seconds (s) or hours (h) Questions 1) How much energy does an electric heater with a power of 200 W consume in 2 minutes? A) 0.01 kj B) 24 kj C) 100 J D) 400 J 2) How much energy is consumed by an oven with an electrical power of 4 kw in use for 2.5 hours? A) 0.9 kwh B) 10kWh C) 10 kj D) kj 3) How long does it take for a kettle with a power of 2 kw to use J of energy? A) 15 s B) s C) 60 min D) 0.07 h 4) What is the power of an electric bulb that gives off 3600 J of energy in 10 minutes? A) 6 kw B) 2.8 kw C) 6 W D) 360 W Page!130!

85 Constructed response question: 5) A water heater has a resistor working with a potential difference of 230 V and a current of 50 A. Calculate the energy consumed by this water heater in 30 minutes. Show all your work. Answers 1) B 2) B 3) A 4) C 5) Example of an appropriate procedure: 1) Calculate the power of the resistor:! =!! = 230! 50! = 1150!! = 1.15!!" 2) Express the time in hours:! = 30!"# 1!h 60!!"# = 0.5!h 3) Calculate the energy consumed by the resistor:! =!! = 1.15!" 0.5!h = 0.575!!"h Answer: The resistor uses kwh of energy in 30 minutes. ** Please note the equivalent answer in Ws is Ws ** Page!131!

86 PoL: Material World F 2bi Electromagnetism: Forces of Attraction / Repulsion I understand that for magnets, different poles attract, while similar poles repel. I would be able to describe and interpret the magnetic field of a magnet and the behavior of a compass in the magnetic field of a magnet Explanation of Concept(s): 1. Every magnet has two poles: North (N) and South (S) N 2. Like poles repel. N Repulsion N S Repulsion S 3. Opposite poles attract. S Attraction N N Attraction S 4. All magnets have a magnetic field. A magnetic field is the space around a magnet where magnetic forces are felt (both attraction and repulsion). Page!132!

87 5. Lines of Force show you the shape, direction, and strength of the magnetic field around a magnet. SHAPE is shown by lines of force which can be straight, curved, circular, etc. DIRECTION is shown by arrowheads. The direction is always from North to South. STRENGTH is shown by how close the lines are to each other. The closer the lines of force are, the stronger the magnetic field. 6. A compass needle is a magnet. Therefore, the compass needle may change direction when it is placed in a magnetic field. The behavior of a compass in the magnetic field of a bar magnet is shown below. Questions: 1. Which of the following correctly illustrates the behavior of a compass in the magnetic field of a bar magnet? A) N S B) N S Page!133!

88 C) N S D) N S 2. Indicate which pole is the North pole of the magnet. a) b) Answer: 1 B 2 a) b) N N Page!134!

89 PoL: Material World B.5. b.i Transformation of Energy: Law of Conservation of Energy I understand and would be able to explain the law of conservation of energy. Explanation of Concept(s): The law of conservation of energy states that energy can neither be created nor destroyed, but it can be transferred or transformed from one form to another. In an isolated system, the total amount of energy remains constant. More specifically, in a frictionless system, mechanical energy remains constant. Multiple Choice Question joules of energy enter a light bulb. 20 joules of energy are transformed into light, how much energy is dissipated as heat? a) 10 joules b) 20 joules c) 30 joules d) 50 joules Short Answer Question 2. Jim is excellent at bowling. He routinely gets several strikes during a typical game. Explain how a strike (i.e. when the bowling ball knocks down all of the bowling pins) illustrates the law of conservation of energy. Answers 1. a 2. The ball rolling down the alley has mechanical energy. The mechanical energy is transferred to the pins upon contact and it causes the displacement of the pins. Page!135!

90 PoL: MW B.5. b.ii i Transformation of Energy: Law of Conservation of Energy I would be able to apply the law of conservation of energy in different situations. Explanation of Concept(s): Examples of the Law of conservation of energy include: The heating elements on a stove convert electrical energy into thermal energy. Hydraulic energy from a waterfall is transformed into mechanical energy to spin a turbine, which is further transformed into electrical energy by a generator. Multiple Choice 1. Consider a dishwasher. What energy path is taken for the dishes to be cleaned? a) electrical mechanical thermal (with some heat lost) b) electrical mechanical thermal c) mechanical thermal electrical d) mechanical electrical thermal Page!136!

91 Constructed Response Question 2. Hydro Electric Energy Describe why all the energy from the water flowing into the turbine is not transformed into electrical energy. 3. Self cleaning ovens have a special cycle (or mode) that will use extremely high temperatures to cook-away any residues or food deposits left within the oven walls. To protect the user from being exposed to extremely hot oven doors during this process, these ovens are typically over - insulated. How do you think this extra insulation affects the efficiency of the oven when used in normal cookingmode. Answers 1. a 2. The water travels along the following path: It flows into the turbine which turns causing the generator to produce electricity which is then transferred along power lines. Due to this long process, not all the water s energy will be converted into electricity. Some will be lost in the process. 3. Since these ovens are more insulated they will allow less heat to escape, as a result, more of the oven s heat will be used for cooking the food, and less will be lost to the oven s surroundings. Page!137!