Unit 6 Solutions. Due Date: Exam Date: Topic 1: Types of Substances - REVIEW. Topic 2: Solubility of Ionic Compounds. Topic 3: Solution Concentration

Transcription

1 Hilton High School Regents / IB Chemistry 11 Name: Set: Due Date: Exam Date: Topic 1: Types of Substances - REVIEW Topic 2: Solubility of Ionic Compounds Topic 3: Solution Concentration Topic 4: Electrolytes Acids, Bases, & Salts Topic 5: Properties of Acids & Bases Topic 6: Neutralization & Titration Lab: Electrolytes Acids, Bases, & Salts

2 Essentials Know, Understand, and Be Able To... Matter is classified as either a pure substance or a mixture of pure substances. A pure substance (element or compound) has a constant composition and constant properties throughout a given sample, and from sample to sample. Mixtures are composed of two or more substances that can be separated by physical means (filtration, distillation, chromatography). When substances are mixed together, either a homogeneous or heterogeneous mixture is formed. A solution is a homogeneous mixture of a solute dissolved in a solvent. Some ionic compounds are soluble in water and dissociate into ions. Other ionic compounds are insoluble in water and form precipitates. Table F: Determining solubility of ionic compounds in water. Kinetic Molecular Theory (KMT) describes the relationships of pressure, volume, temperature, velocity, and frequency and force of collisions among gas molecules. The word concentration describes how much solute has been dissolved in the solvent. Solution are sometimes described as dilute or concentrated. Concentration expressed as Molarity (M), which is the moles of solute dissolved per Liter of solution. Be able to calculate this and be able to calculate how to prepare a solution of given Molarity. An electrolyte is a substance that dissolves in water and forms a solution capable of conducting an electric current. In order to carry current, you must have charged particles that can move freely. Sort compounds as Arrhenius acids, Arrhenius bases, or salts according to their chemical formulae. Behavior of acids described by the Arrhenius Theory. The acidity of alkalinity of a solution can be measured by ph. The relative level of acidity of alkalinity of a solution can be shown by using indicators. Arrhenius acids yield H3O + (hydronium ions) as the only positive ions in an aqueous solution. Arrhenius bases yield OH - (hydroxide ions) as the only negative ions in an aqueous solution. Given properties, identify substances as Arrhenius acids or Arrhenius bases. Identify solutions as acid, base, or neutral based upon ph. Interpret changes in acid-base indicator color. Neutralization: Arrhenius acid reacts with Arrhenius base to form a salt and water. Titration: Laboratory technique in which the volume of a solution of known concentration is used to determine the concentration of another solution. Write simple neutralization reactions when given the reactants. Calculate the concentration or volume of a solution, using titration data and Table T.!1

3 Topic 1 - Types of Substances REVIEW 1. Fill in the blanks: A mixture is a (physical or chemical) combination of two or more pure substances. (heterogeneous or homogeneous) mixtures have uniform composition (i.e. salt water). (heterogeneous or homogeneous) mixtures are not uniform in composition (bucket of dirt). 2. The Matter Flow Chart: Complete this flow chart by placing these terms correctly compounds, heterogeneous, homogeneous, elements Matter Pure Substances Mixtures of Substances 3. Particle Diagrams: a) Identify each picture as a pure substance, or a mixture. b) Identify each of the ones you classified as a substance as either an element or a compound. Identify each of the ones you classified as a mixture as either heterogeneous or homogenous.!2

4 Matter Review 1. Matter is classified as either a pure substance or a mixture of pure substances. a) What are two examples of pure substances 2. A pure substance (element or compound) has a constant composition and constant properties throughout a given sample, and from sample to sample. a) What does it mean to have a fixed ratio of elements? 3. Mixtures are composed of two or more substances that can be separated by physical means. a) What are three physical methods that can be used to separate substances? i) ii) iii) 4. When substances are mixed together, either a homogeneous or heterogeneous mixture is formed. a) What is the difference between a homogeneous and a heterogeneous mixture? 5. A solution is a homogeneous mixture of solute dissolved in a solvent. a) What makes it a homogenous mixture and not a heterogeneous mixture?!3

5 Guided Reading A solution is a homogenous mixture where one substance (the solute) is completely and evenly dispersed in another solvent (the solvent). Making a solution is a physical change - if salt is dissolved, it is still salt and the water is still water. A phase is any part of a system with uniform composition and properties. In a homogenous mixture such as a solution, there is only one phase, meaning the components can not be visually distinguished. A heterogeneous mixture consists of more than one phase, meaning the various components can be visually distinguished. Solutions are homogenous mixtures in which the solute will not settle out of solution over time. In solution the solute exists as atoms, ions, or small molecules. Solutions can exist as solids (alloys), liquids, or gases. An alloy is a combination of two metals. Question: 1. When a substance is dissolved, is it a physical or a chemical change? 2. Describe how an alloy is a solution and give an example. (You ll have to look this up.) Word Bank: heterogeneous mixture solution phase homogenous solute solvent A is a physical combination of two or more pure substances. mixtures have a uniform composition (i.e. salt water). mixtures are not uniform in composition (a bucket of dirt) is the material which is dissolved. is the material which does the dissolving. is the homogenous mixture formed from a solute in a solvent. is any part of a system with a uniform composition.!4

6 Topic 2 - Solubility of Ionic Compounds Activity: Dissolving Salts Simulation 1. Define salt: 2. Go to the following website 3. Click run now. 4. Use your mouse to move the shaker up and down four times to put some table salt particles into the water. a) What is the chemical formula of table salt? b) Is table salt an ionic or covalent compound? How do you know? c) What happens to the solid salt lattice when it hits the water? d) Based on atomic size (radius), which ions are represented by the red dots? The green dots? e) Describe the motion of the ions in the water. f) This is now a solution of salt. Write the chemical formula with the appropriate phase labeled. 5. Now move the shaker up and down many more times to add a lot more salt to the water. What starts to happen? 6. When you ve added enough salt to have a big solid mass of it inside your water, watch what is happening. a) Are some ions in the solid lattice breaking free into the water? b) Are some ions in the water becoming attached to the solid lattice? c) This solution is now in equilibrium. Define equilibrium:!5

7 d) Is this equilibrium a physical or chemical equilibrium? Explain how you decided. e) Look in the upper right hand corner of the screen at the number of ions bound vs. dissolved. What do you notice about these numbers now? f) Explain the equilibrium in the solution in terms of the number of particles bound vs. dissolved. 7. Now use the bottom faucet to drain all the liquid, leaving only the solid lattice. Then use the top faucet to add enough water to cover the solid. a) What happens to the solid? b) Why did the solid salt dissolve in the new water, but it wouldn t dissolve before? c) Define the term saturated: 8. List 3 ways we could speed up the dissolving of salt in water. i) ii) iii) 9. Now click on the tab at the top that says slightly soluble salts and choose Thallium Sulfide from the drop- down menu on the top right. Shake thallium sulfate into the water and observe. a) Describe how thallium sulfate is behaving differently than table salt did. b) What do you think it means to be a slightly soluble salt? c) Look at the numbers of dissolved vs. bound ions in the boxes at the top right. What do you notice? Is this solution at equilibrium? Explain how you decided.!6

8 " " Hilton High School Regents / IB Chemistry 11 Dissociation Dissociate is a shortened form of dis-associate. If an ionic compound dissolves in water, it is because the attraction of water molecules for the ions is able to pull the ions apart from each other, overcoming their ionic bonds and causing them to dis-associate from each other. Dissociation is a PHYSICAL change because it is easily reversed by evaporating the water. Draw pictures showing how water molecules will orient themselves when surrounding these ions. The Hydrogen ends of water molecules are + charged and the Oxygen end is charged. It is useful to draw water like this: K 1+ S 2- Complete the dissociation equations below by putting correct coefficients on each blank. Use the example given below to help you. (Study it carefully!!) The bottom half of Table I will be helpful as well. In #4 be sure to include the CHARGES of the ions. H 2 O K 3 (PO 4 ) (s) 3 K +1 (aq) + 1 (PO 4 ) 3- (aq) H 2 O 1. NaI (s) Na +1 (aq) + I 1- (aq) H 2 O 2. Na 2 S (s) Na +1 (aq) + S 2- (aq) H 2 O 3. CaCl 2 (s) Ca +2 (aq) + Cl 1- (aq) H 2 O 4. Ca 3 (PO 4 ) 2 (s) Ca + (aq) + PO 4 - (aq)!7

9 Using Table F Before you begin, decide if you need help remembering how to turn names into formulas! (You can also just write the formula and check it before you go on determining solubility. Part A Directions: a) Write the chemical formula b) Determine if it is soluble or insoluble in water. 1. Lithium bromide Part B Directions: Write a dissociation equation for each of the SOLUBLE compounds only!! a) b) 2. Potassium hydroxide a) b) 3. Silver nitrate a) b) 4. Silver iodide a) b) 5. Sodium acetate a) b) 6. Aluminum phosphate a) b)!8

10 Hilton High School Regents / IB Chemistry 11 Do you get it? You should know/understand OR be able to: 1. Some ionic compounds are soluble in water and others are not. How can you determine which compounds dissolve in water and which do not? 2. Ionic compounds that do not dissolve in are said to be insoluble. Does this mean that the attraction between ions is great or is the attraction of ions for water greater? 3. Use Table F in order to determine if an ionic compound is soluble or insoluble in water. Write the formula AND name one compound that does NOT dissolve in water. Write the formula AND name one compound that DOES dissolve in water. 4. Draw particle diagrams of a positive ion in solution and a negative ion in solution, with water molecules correctly oriented around it. Positive ion Negative ion!9

11 Topic 3 - Solution Concentration Activity: Kool Solutions Purpose: Each group will be assigned a recipe for making Kool Aid and will need to calculate how much to make. Then everyone will sample the different solutions to see how the different concentrations taste. Materials: ALL FOOD SAFE; measuring cups, spoons, plastic or paper cups. Group 1 Observations using all senses Would you describe the taste as dilute or concentration? Copy the Molarity of this Kool Aid solution here Group 2 Group 3 Group 4 Group 5 Group 6 What connection can you make between the taste of the solution and its Molarity?!10

12 Concentration Solutions are made when one substance is SOLUBLE in another and dissolves. Important Vocabulary Concentration: A measurement of the amount of a solute that is dissolved in a given amount of a solvent. Concentration can be abbreviated [ ]. Qualitative: Two qualitative ways of describing the concentration of solutions are to use the terms dilute and concentrated. Dilute: Concentrated: Quantitative: An exact way of measuring solution concentration. Usually expressed as MOLARITY. 1. Look at the picture below. Which of the two solutions is more concentrated with solute particles? How do you know this? 2. In each pair below, circle the solution which is more concentrated: a) 10 grams of sugar dissolved in 50 ml of solution, OR b) 20 grams of sugar dissolved in 50 ml of solution a) 1.3 moles of NaCl dissolved in 100 ml of solution, OR b) 1.7 moles of NaCl dissolved in 100 ml of solution. a) 1.3 moles of NaCl dissolved in 100 ml of solution, OR b) 1.3 moles of NaCl dissolved in 200 ml of solution 3. Summarize: What does the word concentrated mean, in terms of the relative amounts of solute and solvent particles?!11

13 Molarity Ladder Directions: We are building up to a concept in chemistry known as molarity. For this activity, you need to move up the ladder one step at a time. You need to SHOW YOUR WORK. Rung 1: Nomenclature Iron II phosphate Name Formula KCl Ca(NO3)2 Copper II nitride LiClO Manganese VI oxide Rung 2: Formula Mass Iron II phosphate Name / Formula Formula Mass (g/mol) KCl Ca(NO3)2 Copper II nitride LiClO Manganese VI oxide!12

14 Rung 3: Moles to Grams 2.5 moles Iron II phosphate Name / Formula Answer (g) moles KCl moles Ca(NO3) moles Copper II nitride 1.0 x 10 3 moles LiClO 9.5 x 10-3 moles Manganese VI oxide Rung 4: Grams to Moles 23.0 g Iron II phosphate Name / Formula Answer (moles) 1.33 g KCl 2.0 g Ca(NO3) g Copper II nitride 1.00 g LiClO 2.3 x 10-6 g Manganese VI oxide!13

15 Rung 5: Molarity 2.5 moles Iron II phosphate in 10.0 L Name / Formula Molarity (mol/ L) 0.90 moles KCl in.050 L.0088 moles Ca(NO3)2 in L 2.00 moles Copper II nitride in 4.00 L 0.50 moles LiClO in 2.0 L 25.0 moles Manganese VI oxide in 5.0 L Rung 6: Molarity (Convert grams to moles first, then divide by the volume) Name / Formula Molarity (mol/l) 23 g Iron II phosphate in 10.0 L 1.33 g KCl in.050 L 2.00 g Ca(NO3)2 in L 55.1 g Copper II nitride in 4.00 L 1.00 g LiClO in 2.0 L 2.3 x 10-6 g Manganese VI oxide in 5.0 L!14

16 Rung 7: Molarity (Convert the volume to liters first and then divide the moles by the liters.) Name / Formula Molarity (mol/l) 2.5 moles Iron II phosphate in 85 ml 0.90 moles KCl in 358 cm moles Ca(NO3)2 in 5.0 ml 2.00 moles Copper II nitride in 1000 cm moles LiClO in ml 25.0 moles Manganese VI oxide in 2.5 x 10 4 cm 3 Rung 8: Molarity to grams (Find the number of moles then convert to grams.) Name / Formula Mass of Solute (g) 10.0 L of 2.3 M Iron II phosphate L of 10.0 M KCl L of 2.50 M Ca(NO3) L of 0.15 M Copper II nitride 2.0 L of M LiClO 5.0 L of 5.0 M Manganese VI oxide!15

17 Rung 9: Molarity to Volume (Use the equations to find the volume when everything else is known.) Name / Formula Volume of Solution (L) 10.0 moles of 2.3 M Iron II phosphate moles of 10.0 M KCl moles of 2.50 M Ca(NO3) moles of 0.15 M Copper II nitride 2.0 moles of M LiClO 5.0 mols of 5.0 M Manganese VI oxide Congratulations!! You ve completed the Mol Ladder. Be sure to check your work...!16

18 Calculating Molarity Use the formula given to you in your chemistry reference tables to answer the following questions moles of sugar are dissolved in 1.0 L of water to make a sugar solution. What is the molarity of the solution? grams of NaCl (table salt) are dissolved in water to make 1 L of solution. What is the molarity of the solution. 3. Concentration of 0.5 moles of NaCl in 2.0 L of water. 4. Number of moles of KBr in 10 L of 0.01 M solution. 5. Number of Liters of 2.5 M NaOH required to give 1.5 moles. 6. What is the molarity when 83 grams of NaOH are dissolved to make 325 ml of solution? Review: 7. A solution is made of two parts. The substance that is doing the job of dissolving the other substance is called the. The substance that is being dispersed, or dissolved, is called the. 8. A solution is made using NaCl and water. In this case, the solute is the and the solvent is the. 9. Most solutions used by chemists are aqueous which means they are solution where is the solvent.!17

19 Do you get it? 1. The word concentration describes how much solute has been dissolved in the solvent. Does a high concentration indicate a lot or a little solute has been dissolved in solvent? 2. Solutions are sometimes described as dilute or concentrated. Which of these terms indicates that a lot of H2O has been added? 3. Are solutions homogenous or heterogeneous? 4. One way chemists describe concentration is to express it as molarity (M). Why does molarity have to be represented by a capital (M) and NOT a lowercase (m)? 5. Calculate solution concentration in molarity (M) Where can you find the formula to calculate molarity? What formula is used to calculate molarity? 6. Describe how to prepare a solution, given the molarity desired. Using sentences and/or diagrams, explain how you would make 1.5 L of a 2.0 M NaOH solution. You should tell how many grams of the substance you need to make the solution; not how many moles. You will need to calculate moles first, though.!18

20 Topic 4 - Electrolytes - Acids, Bases, & Salts What is an Electrolyte? For ionic compounds that dissolve in water, describing them as electrolytes is appropriate since the crystal will fall apart in water. An electrolyte is a substance that dissolves in water and forms a solution capable of conducting an electric current. The ability of a solution to conduct an electric current depends upon the concentration of ions that are present. **In other words the MORE IONS there are, the BETTER the solution can conduct electricity! Look at the picture above. Which would be the best electrolyte (best conductor)? To answer this you first need to write out the formula for each compound. Glucose Sodium chloride Calcium chloride In order for a substance to CONDUCT ELECTRICITY (like an electrolyte), 2 conditions MUST exist: 1. There must be CHARGED PARTICLES (ions are an example of a charged particle). 2. The charged particles must be ABLE TO MOVE FREELY (like in a water solution. THINK!! Which of the solutions in the picture is NOT an electrolyte? Why?!19

21 1. Electrolytes (whether they are strong or weak) can be divided into three categories. Write a definition based on the types of ions produced for each kind of electrolyte. Acid: Base: Ionic Salt: 2. Categorize each of the following as an acid, base, or ionic salt: 1. HBr 4. Li2SO4 2. LiBr 3. LiOH 5. H2SO4 6. Ca(OH)2 For the following compounds, check whether it is an electrolyte or a non-electrolyte. If it IS an electrolyte, label it as an ACID, BASE, or IONIC SALT. You may want to refer to Tables K and L for help. 1. NaCl Compound Electrolyte Non-electrolyte 2. CH3OH (methyl alcohol) 3. C3H5(OH)3 (glycerol) 4. HCl 5. C6H12O6 (sugar) 6. CH3COOH (acetic acid) 7. NaOH 8. C2H5OH (ethyl alcohol) 9. NH4OH (NH3 + H2O) 10. H2SO4!20

22 Topic 5 - Properties of Acids & Bases Activity: Acid & Base Simulation 1. Go to the following website 2. Click run now 3. Copy the equation (along with the white, red, and blue particles) that you see below the beaker. a) Name the red ion and the blue ion using Table E on your Reference Tables. b) Why does this equation have a double arrow? c) Explain in your own words what you think this equation means. 4. Click the box on the right that says show solvent. What is a solvent? What is the solvent in this simulation? 5. Click on the circle labeled conductivity on the right. Then use your mouse to lower the black electrode (-) and the red electrode (+) into the liquid. Finally, click on each of the solutions and record your observations: Water Strong Acid Weak Acid Strong Base Weak Base 6. Click on the circle labeled ph Meter on the right. Then use your mouse to lower the ph meter into the liquid. Finally, click on each of the solutions and record both the ph reading AND what you see in the magnifying glass. Water Strong Acid Weak Acid Strong Base Weak Base ph: ph: ph: ph: ph: 7. Distinguish between an acid and a base in terms of ion concentration. 8. Distinguish between a strong acid and a weak acid in terms of ion concentration. 9. Distinguish between a strong base and a weak base in terms of ion concentration.!21

23 Acid, Base, or Salt? The properties of acids and bases are caused by the ions they form in water. Due to the presence of ions, aqueous solutions of both acids and bases are electrolytes. Acids and bases react with each other to form a salt and water. The reaction is a double replacement reaction known as neutralization. (Example: HCl + NaOH NaCl + H2O) Since acid characteristics are caused by hydronium ions and base characteristics are caused by hydroxide ions, there are some differences as well. Acids increase the hydronium ion concentration of water. Hydronium ion concentration is measured on the ph scale. Acids have a ph below (less than) 7. They also taste sour, the taste of hydronium. Since acids are polar molecules with metallic hydrogen, they react with active metals to release hydrogen gas. This single replacement reaction is responsible for the fact that acids corrode metals. Acids can be used to clean metals. Bases on the other hand increase the hydroxide ion concentration of water and reduce the hydronium ion concentration in water. As a result they have a ph above (greater than) 7. Hydroxide ions taste bitter. Bases don t react with metals, but they are not so kind to skin. Bases feel slippery because they dissolve skin. (Dissolved skin makes a great lubricant.) Substances that dissolve skin are called caustic. Bases can be used to unclog drains or to make soap. Aqueous solutions of acids and bases look identical. Indicators, substances that react with acids or bases to show a definite color change, are used to distinguish between them. See the table to the right. Salts are ionic compounds formed during the neutralization reaction between acids and bases. Salts tend not to have the characteristics of either acids or bases because they are generally neutral like water. Salts do dissolve in water, however, to form electrolyte solutions. Fill in the table below based on the reading and your knowledge of chemistry. Characteristic Acids Bases Conductivity ph Taste Indicators Corrosive / Caustic!22

24 !23

25 Interpreting ph Solutions that are acidic have ph values less than 7 in value. Alkaline solutions are basic, so they have ph values greater than 7. An acidic solution has more H +1 ions in it than (OH) -1 ions. The opposite is true of basic solutions. Neutral solutions contain an equal number of H +1 ions and (OH) -1 ions and have a ph value of 7. As ph decreases, the concentration of H + increases As ph changes by one unit, [H + ] changes by a factor of 10 (ph is a logarithmic scale) A ph of 5 compared to a ph of 6: A ph of 5 is 10 times more acidic. A ph of 8 compared to a ph of 5 : A ph of 5 is 1000 times (10x10x10) less acidic. 1. Given ph in the chart below, fill in the other two columns. ph Value [H + ] in scientific notation [H + ] as a decimal value A solution with a ph = 1 is times more concentrated in [H + ] than a solution with a ph = A solution with a ph = 4 is times less concentrated in [H + ] than a solution with a ph = A solution with a ph = 2 is times (more or less) concentrated in [H + ] than a solution with a ph = Given a solution with a [H + ] = 1.0 x 10-6 Molar, what would be the ph of a solution that is 1000 times more concentrated in [H + ]?!24

26 Acids & Bases in Water (IB only)!25

27 More Practice with ph (IB only)!26

28 Topic 6 - Neutralization & Titration Activity: Neutralization 1. How does the concentration of H + compare to the concentration of OH in solution A? 2. How does the concentration of H + compare to the concentration of OH in solution B? 3. How does the concentration of H + compare to the concentration of OH in solution C? 4. Identify the acidic solution in the model. 5. Identify the basic solution in the model. 6. Identify the neutral solution in the model. 7. Based upon the information presented in the key of the Model, draw reactants and products that form when an H + ion is added to an OH ion. 8. What would happen if solution A and solution B were mixed? Explain your answer. 9. Classify the solution that forms in Exercise 2 (when solution A & B are mixed) as acidic, basic, or neutral. Justify your classification in terms of the concentration of H + ions and OH ions. 10. Can a neutral solution contain H + and/or OH ions? Explain.!27

29 Neutralization Reactions (Regents) When an acid reacts with a base, an ionic salt and water are formed. HCl + NaOH H 2 O + NaCl HBr + KOH H 2 O + KBr HNO 3 + NaOH H 2 O + NaNO 3 H 2 SO4 + 2 KOH 2 H 2 O + K 2 SO 4 ( note the equation had to be balanced) 2 HNO 3 + Mg(OH) 2 2 H 2 O + Mg(NO 3 ) 2 (note the equation had to be balanced) A neutral solution is formed when the right number of moles of strong acid reacts with strong base. Neutralization occurs when the concentration of H 3 O + ions equals the concentration of OH - ions. Write the products and balance the equation for each of the following reactions. Example: 2 HBr + 1 Mg(OH)2 1MgBr2 + 2 H2O 1. HNO3 + KOH 2. H2SO4 + NaOH 3. HCl + LiOH 4. H2SO4 + KOH 5. HI + Ca(OH)2!28

30 Neutralization Reactions (IB only)!29

31 Titration Calculations Use the titration equation on Table T. Show all of your work using the ESA method (Equation, Substitute with units, Answer with units). 1. How much 6.0 M HNO3 is needed to neutralize 39 ml of 2.0 M KOH? 2. How much 3.0 M NaOH is needed to neutralize 30.0 ml of 0.75 M H2SO4? 3. What is the concentration of 20 ml of LiOH if it is neutralized by 60 ml of 4 M HCl? 4. What is the concentration of 60 ml of H3PO4 if it is neutralized by 225 ml of 2 M Ba(OH)2? 5. How much 2 M HBr is needed to neutralize 380 ml of 0.1 M NH4OH? The answers to the questions above are all integers. Each answer stands for a letter of the alphabet. Write the correct letters in the spaces below to find the solution to the riddle.!30

32 Do you get it? You should be able to know/understand OR be able to: 1. In the process of neutralization, an Arrhenius acid reacts with an Arrhenius base. a) What two products are ALWAYS formed? (this is how I tell if it is a neutralization equation.) b) Label each compound in the following reaction as an acid, base, salt, or water. HCl + NaOH NaCl + H2O 2. Write simple neutralization reactions when given the reactants. a) Complete the following reaction: H2SO4 + NaOH 3. Calculate the concentration or volume of a solution using titration data and Table T. a) If 50.0 ml of a 3.0 M HNO3 solution completely neutralized ml of KOH, what was the molarity of the KOH solution?!31

33 Regents Question Pack - Unit 6 Test Review Types of Substances: 1. Which physical property makes it possible to separate the components of crude oil by means of distillation? (1) melting point (2) conductivity (3) solubility (4) boiling point 2. One similarity between all mixtures and compounds is that both: (1) are heterogeneous (3) combine in a definite ratio (2) are homogeneous (4) consist of two or more substances 3. When a mixture of water, sand, and salt is filtered, what passes through the filter paper? (1) water, only (3) water and salt, only (2) water and sand, only (4) water, sand, and salt 4. Which must be a mixture of substances? (1) solid (2) liquid (3) gas (4) solution Solubility: 1. Which of the following compounds is least soluble in water? (1) copper (II) chloride (3) iron (III) hydroxide (2) aluminum acetate (4) potassium sulfate 2 Based on Reference Table F, which of these salts is the best electrolyte? (1) sodium nitrate (3) silver chloride (2) magnesium carbonate (4) barium sulfate 3. What is the correct IUPAC name for the compound NH 4 Cl? (1) nitrogen chloride (3) ammonium chloride (2) nitrogen chlorate (4) ammonium chlorate 4. Based on Reference Table I, which change occurs when pellets of solid NaOH are added to water and stirred? (1) The water temperature increases as chemical energy is converted to heat energy. (2) The water temperature increases as heat energy is stored as chemical energy. (3) The water temperature decreases as chemical energy is converted to heat energy. (4) The water temperature decreases as heat energy is stored as chemical energy. 5. What is the correct formula for iron (III) phosphate? (1) FeP (2) Fe 3 P 2 (3) FePO 4 (4) Fe 3 (PO4) 2 6. Given the equation: KNO 3 (s) + H 2 O(l) KNO 3 (aq) As H 2 O(l) is added to KNO 3 (s) to form KNO 3 (aq), the entropy of the system (1) decreases (2) increases (3) remains the same Use this info for #7 & 8: Given the equation for the dissolving of sodium chloride in water: NaCl(s) + H 2 O Na + (aq) + Cl (aq) 7. Describe what happens to entropy during this dissolving process. 8. Explain, in terms of particles, why NaCl(s) does not conduct electricity.!32

34 Use this info for #9-11: Potassium ions are essential to human health. The movement of dissolved potassium ions, K+(aq), in and out of a nerve cell allows that cell to transmit an electrical impulse. 9. What is the total number of electrons in a potassium ion? 10. Explain, in terms of atomic structure, why a potassium ion is smaller than a potassium atom. 11. What property of potassium ions allows them to transmit an electrical impulse? Molarity: 1. How many moles of solute are contained in 200 milliliters of a 1 M solution? (1) 1 (2) 0.2 (3) 0.8 (4) What is the total number of grams of NaI(s) needed to make 1.0 liter of a M solution? (1) (2) 0.15 (3) 1.5 (4) What is the molarity of a solution of NaOH if 2 liters of the solution contains 4 moles of NaOH? (1) 0.5 M (2) 2 M (3) 8 M (4) 80 M 4. What is the molarity of a solution containing 20 grams of NaOH in 500 milliliters of solution? (1) 1 M (2) 2 M (3) 0.04 M (4) 0.5 M Acids & Bases: 1. Which substance is an Arrhenius acid? (1) LiF(aq) (2) HBr(aq) (3) Mg(OH) 2 (aq) (4) CH 3 CHO 2. When 50. milliliters of an HNO3 solution is exactly neutralized by 150 milliliters of a 0.50 M solution of KOH, what is the concentration of HNO3? (1) 1.0 M (2) 1.5 M (3) 3.0 M (4) 0.5 M 3. When the ph of a solution changes from a ph of 5 to a ph of 3, the hydronium ion concentration is (1) 0.01 of the original content (3) 10 times the original content (2) 0.1 of the original content (4) 100 times the original content 4. A sample of Ca(OH) 2 is considered to be an Arrhenius base because it dissolves in water to yield (1) Ca 2+ ions as the only positive ions in solution (2) H 3 O + ions as the only positive ions in solution (3) OH ions as the only negative ions in solution (4) H ions as the only negative ions in solution 5. Which reaction occurs when hydrogen ions react with hydroxide ions to form water? (1) synthesis (2) titration (3) decomposition (4) neutralization!33

35 6. Four flasks each contain 100 milliliters of aqueous solutions of equal concentrations at 25 C and 1 atm. a. Which solutions contain electrolytes? b. Which solution has the lowest ph? c. What causes some aqueous solutions to have a low ph? d. Which solution is most likely to react with an Arrhenius acid to form a salt and water? 7. Which equation represents a double replacement reaction? (1) 2 Na + 2 H 2 O 2 NaOH + H 2 (3) LiOH + HCl LiCl + H 2 O (2) CaCO 3 CaO + CO 2 (4) CH O 2 CO H 2 O 8. The only positive ion found in an aqueous solution of sulfuric acid is the (1) hydroxide ion (2) hydronium ion (3) sulfite ion (4) sulfate ion 9. Which process uses a volume of solution of known concentration to determine the concentration of another solution? (1) distillation (2) substitution (3) titration (4) double replacement 10. Which ph change represents a hundredfold increase in the concentration of H 3 O +1? (1) ph 5 to ph 7 (2) ph 13 to ph 14 (3) ph 3 to ph 1 (4) ph 4 to ph Which compound is an Arrhenius base? (1) CH 3 OH (2) CO 2 (3) LiOH (4) NO Which statement correctly describes a solution with a ph of 9? (1) It has a higher concentration of H 3 O + than OH and causes litmus to turn blue. (2) It has a higher concentration of OH than H 3 O + and causes litmus to turn blue. (3) It has a higher concentration of H 3 O + than OH and causes methyl orange to turn yellow. (4) It has a higher concentration of OH than H 3 O + and causes methyl orange to turn red. 13. Which of these 1 M solutions will have the highest ph? (1) NaOH (2) CH 3 OH (3) HCl (4) NaCl 14. Which species can conduct an electric current? (1) NaOH(s) (2) NaCl (s) (3) H 2 O(l) (4) HCl(aq) 15. A compound whose water solution conducts electricity and turns phenolphthalein pink is (1) HCl (2) HNO 3 (3) NaOH (4) LiCl!34

36 Use this info for #16 18: Indigestion may be caused by excess stomach acid (hydrochloric acid). Some products used to treat indigestion contain magnesium hydroxide. The magnesium hydroxide neutralizes some of the stomach acid. The amount of acid that can be neutralized by three different brands of antacids is shown in the data table below. 16. Based on Reference Table F, describe the solubility of magnesium hydroxide in water. 17. Show a correct numerical setup for calculating the milliliters of HCl(aq) neutralized per gram of antacid tablet for each brand of antacid. 18. Which antacid brand neutralizes the most acid per gram of antacid tablet? 19. Given the following solutions: Solution A: ph of 10 Solution B: ph of 7 Solution C: ph of 5 Which list has the solutions placed in order of increasing H + concentration? (1) A, B, C (2) B, A, C (3) C, A, B (4) C, B, A 20. Which of these ph numbers indicates the highest level of acidity? (1) 5 (2) 8 (3) 10 (4) According to the Arrhenius theory, when a base dissolves in water it produces (1) CO 3 2 as the only negative ion in solution (3) NH 4 +1 as the only positive ion in solution (2) OH -1 as the only negative ion in solution (4) H +1 as the only positive ion in solution 22. Which solution when mixed with a drop of bromthymol blue will cause the indicator to change from blue to yellow? (1) 0.1 M HCl (2) 0.1 M NH 3 (3) 0.1 M CH 3 OH (4) 0.1 M NaOH!35

37 Use the following info for questions #23 26: A titration setup was used to determine the unknown molar concentration of a solution of NaOH. A 1.2 M HCl solution was used as the titration standard. The following data were collected. 23. Calculate the volume of NaOH solution used to neutralize 10.0 ml of the standard HCl solution in trial 3. Show your work. 24. According to Reference Table M, what indicator would be most appropriate in determining the end point of this titration? Give one reason for choosing this indicator. 25. Calculate the molarity of the unknown NaOH solution using data from Trial 3. Your answer must include the correct number of significant figures and correct units. 26. Explain why it is better to use the average data from multiple trials rather than the data from a single trial to calculate the results of the titration. Use this info for Questions #27 & 28: Calcium hydroxide is commonly known as agricultural lime and is used to adjust the soil ph. Before the lime was added to a field, the soil ph was 5. After the lime was added, the soil underwent a 100-fold decrease in hydronium ion concentration. 27. What is the new ph of the soil in the field? 28. According to Reference Table F, calcium hydroxide is soluble in water. Identify another hydroxide compound that contains a Group 2 element and is also soluble in water!36