Unit 4. Compounds & Mixtures

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Oswin Shelton
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1 Unit 4 Compounds & Mixtures

2 Homework for Unit 4 1. Vocab for Unit 4; due: 2. Pg 81 (1-7), Pg 83 (1-7), Pg 85 (1-6) complete sentences; due: 3. Pg 149 (1-4), Pg 169 (1-4), Pg 173 (1-7) complete sentences; due: 4. Pg 87 (1-4), Pg 91 (1-6), Pg 93 (1-6) complete sentences; due: 5. Pg 105 (1-5), Pg 107 (1-5), Pg 111 (1-4) complete sentences; due: 6. Solubility Homework; due: 7. Pg 113 (1-5), Pg 119 (1-7), Pg 131 (1-5), Pg 133 (1-4) NO Sentences; due: 8. Pg 135 (1-5), Pg 137 (1-5), Pg 141 (1-4) complete sentences; due: 9. Pg 191 (1-6), Pg 193 (1-5), pg 195 (1-5) complete sentences; due: 10. Pin the Tail on the ph Scale; due: 11. Pg 197 (1-7), Pg 203 (1-8), Pg 205 (1-6), NO sentences; due: 12. Review packet; due:

3 Vocabulary for Unit 4 Please define the following words. Homework #1 due: Acid Base Chemical Bond Chemical Equation Chemical Formula Chemical reaction Coagulation Coefficient Colloid Concentrated Solution Covalent Bond Diatomic Molecule Dissolve Distillation Dilute Solution Electrolysis Electrolyte Element Emulsion Filtration Hydroxyl Ion Indicator Insoluble Ion Ionic Bond Law of Conservation of Matter Mixture Molecule Neutral Neutralization ph Scale Pollution

4 Product Reactant Salt Saturated Solution Soluble Solubility Solute Solution Solvent Subscript Supersaturated Solution Suspension Unsaturated solution Valence Electrons

5 Compounds, Molecules & Mixtures Homework #2 due Warm-up: - Define element: - Define atom: Element of the day: Properties: Bohr Diagram: p + = n 0 = e - = Lewis Dot Diagram: Classification: Phase: Compound: Two or more Chemically combined together. - Examples: Carbon Dioxide: Water: Sugar: Salt: Rust: - Properties of compounds: Remember a chemical change results in new. Which means that the properties of each individual element before being combined together chemically are very from the properties of the compound. o Hydrogen: colorless,, gas. Highly explosive. o Oxygen: colorless,, gas. Combustible o Water (chemical combination {compound} of hydrogen and oxygen): wet, clear, liquid. Puts out fire and safe to drink. - Forming and separating compounds: Compounds are formed and separated by means.

6 Molecules: The smallest part of a with all of the properties of that. - NaCl: + - H 2 O - 2 H 2 O - 3 H 2 O - Diatomic molecules: Some elements travel in pairs usually o Hydrogen gas: Oxygen Gas: Nitrogen gas: Mixtures: Two or more substances combined: Examples: - Making a mixture: In a mixture the substances are or combined by physical means. - Remember during a physical change no new substance is formed. Which means that each individual substance maintains its original properties. o In a bag of Skittles there is a mixture of orange, grape, lemon and lime flavors. Each individual Skittle still tastes like their respective flavors. - Separating a mixture: since mixtures are formed by physical means, they are also separated by means. Is it a mixture, compound, diatomic molecule or element? 1. M&M s 6. O 2 2. C 6 H 12 O 6 7. NH 3 3. NaCl 8. Mg 4. H 2 O 9. Iron filings and sulfur in a bowl 5. H Al

7 Chemical Formulas & Equations Warm-up: - Define compound: Homework #3 Due: - How are compounds formed? - Define mixture: - How are mixtures formed? - Define Molecule: Element of the day: Properties: Bohr Diagram: p + = n 0 = e - = Lewis Dot Diagram: Classification: Phase: Chemical Symbols: way of writing the names of elements. - 1 st letter: - 2 nd letter: Chemical Formulas: The shorthand way of writing a - H 2 O - C 6 H Subscripts: SUB means, or. - A subscript the smaller font number to the lower of an element. - It is used to indicate the number of of an element Writing Chemical Formulas - Al 2 O 3 o Molecules of Al 2 O 3 o Atoms of Aluminum o Atoms of Oxygen

8 - 2 Al 2 O 3 o Molecules of Al 2 O 3 o Atoms of Aluminum o Atoms of Oxygen Chemical Equations: statement in which chemical are used to describe a chemical reaction (chemical change). Reactants *Items you start with Products * Items that are the end result Law of Conservation of Matter: - Matter cannot be or, only transfer from one form to another. - Also means that what ever you have in the beginning of the reaction must balance out with the end products. Balanced Chemical Equations 1. 2.

9 Chemical Bonding Warm-up: - What is a chemical formula? Homework #4 Due: - What is a chemical equation? - Describe the Law of Conservation of Matter: Element of the day: Properties: Bohr Diagram: p + = n 0 = e - = Lewis Dot Diagram: Classification: Phase: Compound: two or more elements combined together. Glucose: ** All of these compounds contain the same elements Citric Acid: yet, combine differently to make different compounds** Vitamin C: Chemical Bonding: the of atoms to form substances. - The properties of these substances are different from those of the original substance Hydrogen: colorless, gas that is explosive Oxygen: colorless, gas that is combustible Water: the chemical combination of hydrogen and oxygen gas is a liquid and is safe to drink. Chemical Bond: the force of between 2 or more atoms, holding the atoms together.

10 Disclaimer: Atoms and chemical bonds cannot be seen with our eyes. Experiments help scientists to determine a theory of chemical bonding. The use of models helps to explain this theory. Valance electrons: The electrons that are located in the most energy level of an atom. These are the electrons usually used to create a bond. Oxygen Sodium 1 St 1 st 2 nd 2 nd 3 rd Not all atoms bond in the same manner, some do not bond at all. The number of electrons in the outer most energy level determines whether an atom will form a bond. Atoms of the noble gases do not normally form bonds, because their valance shell already contains 8 electrons. Atoms bond in order to fill the outermost level. So, atoms with less than 8 valance electrons are more reactive. Atoms bond by, or electrons in order to fill their valance shell. Types of Chemical Bonds 1. Ionic Bonds: Force of attraction between charged ions a. Ions: charged atom that forms during a chemical change when one or more are transferred from one atom to another. b. Positive ions: forms when an atom one or more electrons so the overall charge is c. Negative Ions: forms when an atom one or more electrons so the overall charge is d. Metals usually electrons, nonmetals usually electrons e. Neutral Compounds: form when a metal and nonmetal react together and the number of gained equals the number of lost. 2. Covalent Bonds: Force of attraction between the nuclei of atoms and the electrons that are between them:

11 Solutions Warm-up: - Identify the parts of the Chemical Equation below: Homework #5 Due: H 2 + O 2 2H 2 O - Is this equation balanced? If not, please balance it. - Please identify the number of atom of each element: - H 2 O - C 6 H 12 O 6 - Al 2 O 3 A Solution is: A type of in which one substance is evenly (mixed) into another substance. - Examples: **Remember: Mixtures are physically combined together and are separated by physical means!** All solutions are made when one substance dissolves in another substance. A solution of salt and water forms when salt dissolves into water. 2 parts of a solution: 1. Solute: the that dissolves a. Examples: 2. Solvent: the that the solute dissolves into a. Examples: Substances can be classified as: 1. Soluble: a. Examples: 2. Insoluble: a. Examples:

12 There are three main ways to change the rate at which a substance dissolves 1. Stirring the solute: 2. Change the temperature of the solvent: 3. Smaller particle size for the solute: How are the strengths of solutions described? 1. Dilute solutions: 2. Concentrated solutions: Since the temperature of a solvent allows some substances to dissolve at different rates, we can classify solutions based on how much they can hold for a certain temperature. 1. Unsaturated solutions: a solution that contains solute than it can hold at a certain temperature. Which means that there is still room for solute. 2. Saturated solutions: a solution that contains of the solute that it can hold at a certain temperature. Which means that there is not room for solute. 3. Supersaturated: a solution that contains solute than it can hold at a certain temperature. Which means that there is solute settle at the bottom of the glass.

13 Solubility Graphs Warm-up: - What is a Chemical Bond? Homework #6 Due: - What are valence electrons? - Define Ionic Bond: - Define covalent bond: Solubility Graphs Solubility graphs have been developed by scientists to summarize the solubility (how much solute can be dissolved into a solvent) of various substances at various temperatures. What does the X-Axis represent? What does the Y- Axis represent? 1. How would you describe the solubility of NaCl, as the temperature changes? 2. How would you describe the solubility of KBr, as the temperature changes? 3. What is the solubility of NaCl at 20 C? 4. What is the solubility of NaClO 3 at 20 C? 5. What is the solubility of KBR at 20 C? 6. Which solution has a solubility of 50 grams of solute per 100g of water at 35 C?

14 Solubility Homework (#6) Please complete the following using the graph below. Due: 1. Why do the temperatures on the graph only go from 0º C to 100º C? 2. Which substance is most soluble at 60º C? 3. Which two substances have the same solubility at 80º C? 4.Which substance s solubility changes the most from 0º C to 100º C? 5.Which substance s solubility changes the least from 0º C to 100º C? 6. What is the solubility of potassium nitrate at 90º C? 7. At what temperature does potassium iodide have a solubility of 150 g/ 100 cm3 water? 8. You have a solution of sodium nitrate containing 140 g at 65º C. Is the solution saturated, unsaturated, or supersaturated? 9. You have a solution of potassium chlorate containing 4 g at 65º C. How many additional grams of solute must be added to it, to make the solution saturated?

4. At 20 o C, a saturated solution of sodium nitrate contains 100 grams of solute in 100 ml of water. How many grams of sodium chlorate must be added to saturate the solution at 50

15 1. Which of the salts shown on the graph is the least soluble in water at 10 o C? 2. Which of the salts shown on the graph has the greatest increase in solubility as the temperature increases from 30 degrees to 60 degrees? 3. Which of the salts has its solubility affected the least by a change in temperature? 4. At 20 o C, a saturated solution of sodium nitrate contains 100 grams of solute in 100 ml of water. How many grams of sodium chlorate must be added to saturate the solution at 50 o C? 5. At what temperature do saturated solutions of potassium nitrate and sodium nitrate contain the same weight of solute per 100 ml of water? 6. What two salts have the same degree of solubility at approximately 19 o C? 7. How many grams of potassium chlorate must be added to 1 liter of water to produce a saturated solution at 50 o C? 8. A saturated solution of potassium nitrate is prepared at 60 o C using 100.mL of water. How many grams of solute will precipitate out of solution if the temperature is suddenly cooled to 30 o C? 9. What is the average rate of increase for the solubility of KNO 3 in grams per 100 ml per degree Celsius in the temperature range of 60 o C to 70 o C? 10. If 50. ml of water that is saturated with KClO 3 at 25 o C is slowly evaporated to dryness, how many grams of the dry salt would be recovered? 11. Thirty grams of KCl are dissolved in 100 ml of water at 45 o C. How many additional grams of KCl are needed to make the solution saturated at 80 o C? 12. What is the smallest volume of water, in ml, required to completely dissolve 39 grams of KNO 3 at 10 o C? 13. What is the lowest temperature at which 30. grams of KCl can be dissolved in 100 ml of water? 14. Are the following solutions saturated, unsaturated or supersaturated (assume that all three could form supersaturated solutions) a. 40. g of KCl in 100 ml of water at 80 o C b g of KNO 3 in 100 ml of water at 60 o C c. 80. g of NaNO 3 in 100 ml of water at 10 o C

16 Suspensions Warm-up: - What is a solution? Homework #7 Due: - Define Saturated Solution: - Define unsaturated solution: - Define Supersaturated Solution: Suspension: a of two materials or more that are when they have been left alone for a period of time. When a substance, such as soil is added to a jar of water, the water is cloudy to begin with. If the water stands unbothered for a period of time, the soil settles to the bottom of the jar. Originally it appeared to be Mixed into the water, and over time is separated out. This is considered to be a temporary mixture. The particles in a suspensions are, or too tiny to be seen. They are in their smallest form, either atoms or molecules. When light passes through a suspension, the light is. This is one why to determine that it is NOT a solution. Suspensions can be separated by, and. Settling: allowing the particles to sink to the bottom. Larges particles are on the ; finer particles are on the. Filtration: separation of particles in a suspension by passing the suspension through paper or some other porous material (material with holes in it). Coagulation: use of to make the particles in a suspension clump together.

17 Separating a Solution Warm-up: - What is a suspension? Homework #8 Due: - What are three ways that a suspension can be separated? - What is filtration? **Remember: a solution is a type of, which means it is formed and separated by physical means. ** We have already learned about several physical changes:,,,,. We can use these means to help separate a solution. For our example we will use saltwater. 1. Evaporation (Boiling) Ex: You have just gotten out of the water at the beach. It s a really hot day and before you know it there is no more water on your skin. What is left behind on your skin?. As a result of a solution of salt water was just separated. The salt stayed on your skin, where did the water go? 2. Condensation Ex: Air is a mixture of gasses including helium, hydrogen, carbon dioxide, oxygen, nitrogen and vapor. The same water vapor that was just evaporated off of your skin. We can use condensation to remove the vapor from the air. Remember as heat is removed from the air (or the air is cooled) condensation will form on a glass. If the air around you is cooled the water will collect on that cooler surface. We have just separated water from air. That seems like a lot of work just to separate salt water into its two parts. An easier method is something called. 3. Distillation - Combines the processes of and to separate a solution into its two parts. - 1 st : the solution is boiled causing the solvent to become a - 2 nd : The gas form of the solvent flows into a glass tube that is covered with cold water. This cold water is used to the solvent back into the liquid state. - 3 rd : The solvent drips slowly into the beaker on the other side. This leaves you will the pure on one side, and the remains back in the original beaker.

18 Identify describe the unit: 1. and the parts of distillation More questions: 1. Is this a physical or chemical process? 2. If you use distillation to separate a mixture of two liquids, the liquids must have different? 3. The first liquid to boil will have the boiling point. 4. In a mixture of food coloring and water, which boils first? What does this tell you about the boiling point of food coloring? 5. What is distilled water? A mixture, element or compound?

19 Acids, Bases and the ph Scale Warm-up: - Describe all of the steps for distillation: Homework #9 due Acids: - Any compound that the number of (H + ) ions when dissolved in - Substance that produces gas when it reacts with a Common acids: - Hydrochloric Acid: - Citric Acid: - Acetic Acid: - All chemical formulas for acids begin with an Properties of acids: - Tastes - : Burns skin and eyes - Some acids can help conduct electric current when dissolved in water: called an Bases: - Any compound that the number of (OH - ) ions when dissolved in - Substance that is when a reacts with Properties of bases: - Feels - Tastes - Can be to skin and eyes Common bases: - Potassium Hydroxide: - Sodium Hydroxide: - In general most products are bases such as; soap, detergent and ammonia - All chemical formulas for bases end with an

20 Indicators: - A substances that changes in the presences of an or a - Litmus: and red pieces of paper that changes colors in the presence of an acid or base. o Red litmus: Turns in a base Stays in an acid o Blue litmus: Stays in a base Turns in an acid Strengths of acids and bases: - Acids and bases can be considered or depending on the amount of or ions that they contain. - If the solution contains a lot of either of these ions it is - If the solution contains very little of either of these ions it is ph Scale: - Used to compare the strengths of acids and bases Acid Base

21 Neutralization Warm-up: - Describe an acid: Homework #10 due - Describe a base: - Describe a ph scale Neutralization: a reaction between an and a to produce a (which is neither an acid or a base) and ( a neutral liquid) Salts: substance formed from the ion of an acid and the ion of a base. Acid + Base Salt + Water

22 Separating a Compound Warm-up: - What is neutralization? Homework #11 due - What is the chemical equation for neutralization? 1. Electrolysis: 2. Please answer the following using the diagram below: a. What liquid is in the tubes? b. More bubbles are in the (right/left) tube. c. The substance that is attracted to the right side must be (positive/negative). d. (Like/opposite) charges are attracted to each other. e. The liquid substance in the tubes must be a(n) (element/compound) f. The particles of hydrogen must have a (+/-) charge g. If the gas in the tube on the right has a volume of 20 ml, then the volume on the left is: h. If 18 ml of hydrogen is collected then ml of oxygen is collected. i. If 7 ml of oxygen is collected, then ml of hydrogen is collected. 3. What kind of energy does electrolysis use? 4. Hydrogen gas is located in the tube on the (right/left) 5. Oxygen gas is located in the tube on the (right/left) 6. The ratio if hydrogen gas to oxygen gas collected is: 7. Is this a physical or chemical process? 8. Is this process exothermic or endothermic?

23 Pin the Tail on the ph Scale (# ) Due: Part 1: 1. Please describe the properties of an acid: 2. Please describe the properties of a base: 3. What is an indicator? Please give an example: 4. Another word for base is alkali, which will be used in this worksheet. Activity 1. Please go to the following web address: ds/litmus.htm 2. Type in your name 3. Read the directions in the upper left of the screen. Your first job is to make a predication as to whether something is an acid (click red), base (click blue) or neutral (click green). Please record your prediction in the table below: Substance Prediction Test Were you correct? Vinegar Water Baking Powder Alka Seltzer Cola Lemon Juice Tea Oven Cleaner Battery Acid 4. After you have made predictions for each item. Click the word TEST which appears first next to vinegar. Based on the litmus test results you must determine is the substance is an acid, alkali (base) or neutral, just like you did before. Please record this in the table as well. In the third column please indicated if you were correct it is ok if you were not. 5. If you do not have access to the Internet please see you teacher by: to make other arrangements.

24 6. You DO NOT need to print out your final results, you just wrote them all in the chart. Part 2: Materials: three pieces of blue and red litmus paper, five pieces of ph paper, and safe materials from home. Procedure: 1. Each student will use the litmus paper to find three acids and two bases using SAFE materials from home. 2. You are response for contrasting a table to organize the data that you have collected, on a separate piece of paper. 3. When each of the acids or bases are found the litmus paper must be attached to your table with the material tested and whether it is an acid or a base. 4. After the acids and bases have been identified the student will then use ph paper to determine the approximate ph of the material. Please write down the color to which the paper changes immediately after you test the material. The ph paper must also be attached to your table with the color listed that it changed to. 5. When the students return to class they will be required to place each individual acid and base on the ph scale provided for them in the appropriate location for full credit. You will be allowed to look at the color scale on the ph box to help you determine the ph of the material. You need to be close, but not exact. This project is due on

Name Date. 9. Which substance shows the least change in solubility (grams of solute) from 0 C to 100 C?

Name Date. 9. Which substance shows the least change in solubility (grams of solute) from 0 C to 100 C? Solubility Curve Practice Problems Directions: Use the graph to answer the questions below. Assume you will be using 100g of water unless otherwise stated. 1. How many grams of potassium chloride (KCl)