STOICHIOMETRY. Chapter Quiz. Fill in the word(s) that will make each statement true

Transcription

1 STOICHIOMETRY Chapter Quiz Fill in the word(s) that will make each statement true. 1. The 1 in a balanced chemical equation also reveal the mole ratios of the substances involved The number of moles of a product can be calculated from a given number of moles of In mass-mass calculations, the molar mass is used to convert mass to In addition to mass, the only quantity conserved in every chemical reaction is According to the equation: 2NO(g) + O 2(g) 2NO 2(g), 22.4 L of O 2 will react with 5 L of NO at STP. Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 6. The excess reagent determines the amount of product formed in a reaction. 7. In the reaction 2CO(g) + O 2(g) 2CO 2(g), using 4 moles of CO to react with 1 mole of O 2 will result in the production of 4 moles of CO 2.

2 8. To calculate the percent yield of a reaction, you use the following relationship: theoretical yield 100 actual yield 9. The total mass of the excess reagent and the limiting reagent is equal to the total mass of the products. 10. The actual yield is equal to the theoretical yield. STOICHIOMETRY Chapter Test A A. Matching Match each description in Column B with the correct term in Column A. Write the letter of the correct description on the line. Column A Column B 1. actual yield a. the ratio of the actual yield to the theoretical yield, expressed as a percentage 2. limiting reagent b. the amount of product formed when a reaction is carried out in the laboratory c. the reactant that determines the amount of product that can be formed in a reaction 3. theoretical yield d. the reactant that is not completely used up in a reaction 4. stoichiometry e. the calculated amount of product that might be formed during a reaction 5. percent yield f. the calculation of quantities in chemical equations 6. excess reagent B. Multiple Choice

3 Choose the best answer and write its letter on the line. 7. Which of these expressions is an incorrect interpretation of the balanced equation? 2S(s) + 3O 2(g) 2SO 3(g) a. 2 atoms S + 3 molecules O 2 2 molecules SO 3 b. 2 g S + 3 g O 2 2 g SO 3 c. 2 mol S + 3 mol O 2 2 mol SO 3 d. none of the above 8. In a chemical reaction, the mass of the products a. is less than the mass of the reactants. b. is greater than the mass of the reactants. c. is equal to the mass of the reactants. d. has no relationship to the mass of the reactants. 9. How many liters of oxygen are required to react completely with 1.2 liters of hydrogen to form water? 2H 2(g) + O2(g) 2H 2(g) a. 1.2 L c. 2.4 L b. 0.6 L d. 4.8 L Chapter 12 Stoichiometry How many molecules of NO 2 are produced when molecules of N 2O 4 are decomposed according to the following equation? a. 4 c N 2O 4(g) 2NO 2(g) b d How many liters of CO(g) at STP are produced when 68.0 g of CaCO 3(s) is heated according to the following equation? CaCO 3(s) CaO(s) + CO 2(g) a L c L b L d L 12. A reaction that has been calculated to produce 60.0 g of CuCl 2 actually produces 50.0 g of CuCl 2. What is the percent yield?

4 a % c. 83.3% b. 96.1% d. 120% 13. When 0.2 mol of calcium is mixed with 880 g of water, 4.48 L of hydrogen gas forms (at STP). How would the amount of hydrogen produced change if the mass of water were decreased to 220 g? a. Only one half of the volume of hydrogen would be produced. b. The volume of hydrogen produced would be the same. c. The volume of hydrogen produced would double. d. No hydrogen would be produced. 14. The equation for the complete combustion of methane is CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(l) To calculate the number of grams of CO 2 produced by the reaction of 29.5 g of CH 4 with O 2, the first conversion factor to use is 1 mol CH g CH a. c g CH 1 mol CH mol O2 b. 1 mol CO d g CH 2 mol CO In any chemical reaction, the quantities that are conserved are a. the number of moles and the volumes. b. the number of molecules and the volumes. c. mass and number of atoms. d. mass and moles. Questions 16, 17, and 18 refer to the following equation: 3Cu(s) + 8HNO 3(aq) 3Cu(NO 3) 2(s) + 2NO(g) + 4H 2O(l) 16. Calculate the number of moles of water produced when 3.3 mol of Cu(NO 3) 2 are formed in the reaction. a. 4.4 mol c. 4.9 mol b. 6.6 mol d. 8.8 mol 17. How many grams of Cu would be needed to react with 2.0 mol HNO 3? a g c g b g d g 18. If you could drop 12 atoms of copper into a beaker containing nitric acid, how many molecules of NO would be produced? a. 2 c. 8 b. 4 d. 12

5 C. Problems Solve the following problems in the space provided. Show your work. 19. What is the limiting reagent when g of nitrogen react with 10.7 g of hydrogen according to this balanced equation? N 2(g) + 3H 2(g) 2NH 3(g) 20. How many grams of CO are needed to react with an excess of Fe 2O 3 to produce 558 g Fe? The equation for the reaction is: Fe 2O 3(s) + 3CO(g) 3CO 2(g) + 2Fe(s) 21. How many grams of butane (C 4H 10) must be burned in an excess of O 2 to produce 15.0 g of CO 2? 2C 4H 10(g) + 13O 2(g) 8CO 2(g) + 10H 2O(g) 22. a. If 4.0 g of H 2 are made to react with excess CO, how many grams of CH 3OH can theoretically be produced according to the following equation? CO(g) + 2H 2(g) CH 3OH(l) b. If 28.0 g of CH 3OH are actually produced, what is the percent yield? D. Essay Write a short essay for the following. 23. What is the importance of the coefficients in a balanced chemical equation? E. Additional Problems Solve the following problems in the space provided. Show your work. 24. A g sample of Al 2(SO 4) 3 is made to react with 450 g of Ca(OH) 2. A total of 596 g of CaSO 4 is produced. The balanced equation is: a. What is the limiting reagent in this reaction? Al 2(SO 4) 3(aq) + 3Ca(OH) 2(aq) 2Al(OH) 3(s) + 3CaSO 4(s) b. How many moles of excess reagent are unreacted? 25. How many liters of O 2 are needed to react completely with 10.0 L of H 2S at STP according to the following reaction? 2H 2S(g) + 3O 2(g) 2SO 2(g) + 2H 2O(g) 26. The decomposition of potassium chlorate gives oxygen gas according to the reaction: 2KClO 3(s) 2KCl(s) + 3O 2(g)

6 How many grams KClO 3 are needed to produce 5.00 L of O 2 at STP? 27. Suppose that the reaction described in question 26 produces 4.80 L of O 2 in the laboratory. What is the percent yield? STOICHIOMETRY Chapter Test B A. Matching Match each term in Column B with the correct description in Column A. Write the letter of the correct term on the line. Column A Column B 1. the substance that determines the amount of product that can be formed in a reaction a. percent yield 2. the amount of product that forms when a reaction is carried out in the laboratory b. limiting reagent 3. the calculation of quantities in chemical equations c. theoretical yield 4. the ratio of the actual yield to the theoretical yield expressed as a percent d. stoichiometry 5. the substance that is present in enough quantity to react with a limiting reagent e. actual yield 6. the maximum amount of products that could be formed from given amounts of reactants f. excess reagent B. Multiple Choice Choose the best answer and write its letter on the line.

7 7. In a chemical reaction a. mass is conserved. c. moles are conserved. b. atoms are conserved. d. both mass and atoms are conserved. 8. Which of the following is a correct interpretation of this balanced equation? 2Al(s)+ 3Pb(NO 3) 2(aq) 2Al(NO 3) 3(aq)+ 3Pb(s) a. 2 atoms Al + 3 molecules Pb(NO3) 2 2 molecules Al(NO 3) atoms of Pb b. 2 grams Al + 3 grams Pb(NO 3) 2 2 grams Al(NO 3) grams Pb c. 2 moles Al + 3 moles Pb(NO 3) 2 2 moles Al(NO 3) moles Pb d. both a and c 9. If 3.0 moles of HCl are consumed in the reaction below, how many moles of FeCl 3 are produced? 6HCl + Fe 2O 3 2FeCl 3 + 3H 2O a mol c. 2.0 mol b. 1.0 mol d. 4.0 mol 10. Given the equation 2H 2O 2H 2 + O 2, how many moles of H 2O would be required to produce 2.5 moles of O 2? a. 2.0 mol c. 4.0 mol b. 2.0 mol d. 5.0 mol 11. If 3.00 mol of CaCO 3 undergo decomposition to form CaO and CO 2 how many grams of CO 2 are produced? a g c g b g d. 132 g 12. If CuO + H 2 Cu + H 2O, how many moles of H 2O are produced when 240 grams of CuO react? a. 1.0 mol c. 18 mol b. 3.0 mol d. 54 mol 13. Given the balanced equation 16HCl + 2KMnO 4 2KCl + 2MnCl 2 + 5Cl 2 + 8H 2O, if 1.0 mol of KMnO 4 reacts, how many moles of H 2O are produced? a mol c. 4.0 mol b. 2.0 mol d. 8.0 mol 14. Based on the equation in question 13, how many grams of KCl are produced when 1.0 mol of KMnO 4 reacts? a. 1.0 g c. 150 g b. 75 g d. 158 g

8 15. If 110 grams of HCl are used in the reaction 6HCl + Fe 2O3 2FeCl 3 + 3H 2O, how many moles of FeCl 3 are produced? a. 1.0 mol c. 3.0 mol b. 2.0 mol d. 6.0 mol 16. In the reaction Zn + H 2SO 4 ZnSO 4 + H 2 how many grams of H 2SO 4 are required to produce 1.0 gram of H 2? a. 1.0 g c. 49 g b. 2.0 g d. 98 g 17. If 18 grams of carbon react with oxygen to produce carbon dioxide, of H 2 how many molecules of oxygen would be required? a. 1.5 molecules c molecules b. 48 molecules d molecules 18. Given the reaction 2NO(g) + O 2(g) 2NO 2(g), if 6.5 L of O 2 react at STP, how many liters of NO 2 are produced? a. 6.5 L c. 26 L b. 3.2 L d. 13 L 19. Given the reaction Zn + 2HCl ZnCl 2 + H 2, if 2.0 mol Zn and 5.0 mol HCl are allowed to react a. Zn is the limiting reagent. c. 1.0 mol of ZnCl2 is produced. b. HCl is the limiting reagent. d. 5.0 mol of H2is produced. 20. Once the reaction in question 19 is completed, how many moles of excess reactant remain? a. 3.0 mol c. 4.0 mol b. 1.0 mol d. 2.0 mol 21. Given the reaction CaCO 3(s) + CaO(s) + CO 2(g), if 50.0 g of CaCO 3 react to produce 20.0 g of CO 2 what is the percent yield of CO 2? a. 66.7% c. 90.9% b. 40.0% d. 250 % C. Problems Solve the following problems in the space provided. Show your work. 22. Ammonia, NH 3, is a typical ingredient in household cleaners. It is produced through a combination reaction involving N 2(g) and H 2(g). If 12.0 mol of H 2(g) react with excess N 2(g), how many moles of ammonia are produced?

9 23. The compound tin(ii) fluoride, or stannous fluoride, once was a common ingredient in toothpaste. It is produced according to the following reaction: Sn(s) + 2HF(g) SnF 2(s) + H 2(g) If 45.0 grams of HF react with Sn, how many grams of stannous fluoride are produced? 24. The combustion of methane, CH4(g), can be described by the following CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(g) If 150 moles of carbon dioxide are produced, what mass, in grams, of methane is required? 25. If aluminum reacts with oxygen according to the following equation: 4Al(s)+ 3O 2(g) 2Al 2O 3(s) what mass, in grams, of the product would be produced if 625 ml of oxygen react at STP? 26. Given the following reaction: CaCO 3(s) CaO(s) + CO 2(g), if 50.8 grams of CaCO 3 react to produce 26.4 grams of CaO, what is the percent yield of CaO? D. Essay Write a short essay for the following. 27. Based on the following general reaction, if 1.0 mole of A is allowed to react with 2.0 moles of B, which reactant is the limiting reactant and what amount of A 2B 3 can be produced? 2A+ 3B A 2B 3 E. Additional Problems Solve the following problems in the space provided. Show your work. 28. In photosynthesis, plants use energy from the sun in combination with carbon dioxide and water to form glucose (C 6H 12O 6) and oxygen. If 4.50 moles of water react with carbon dioxide, what mass of glucose is produced? 29. Acetylene gas (C 2H 2) is used in welding and produces an extremely hot flame according to the reaction: 2C 2H 2(g) + 5O 2(g) 4CO 2(g) + 2H 2O(g) if g of acetylene burn completely, how many grams of carbon dioxide are produced?

10 30. Given the following reaction: 3H 2SO 4 (aq) + Ca 3 (PO 4) 2(s) 3CaSO 4(s) + 2H 3PO 4(aq), if 1.25 kg of H 2S) 4 react, how many kilograms of H 3PO 4 are produced? 31. Ammonia and copper (II) oxide react according to the following: 2NH 3(g) + 3CuO(s) N 2(g) + 3Cu(s) + 3H 2O(g) if 57.0 g of ammonia are combined with g of copper (II) oxide: a. Identify the limiting reactant. b. How much of the excess reactant remains, in moles? c. What mass of nitrogen gas is produced, in grams? 32. If ammonia reacts according to the following equation, how many kilograms of NO could be produced from 10.0 kg of NH 3 if the percent yield of NO is 80.0%? 4NH 3(g) + 5O 2(g) 4NO(g) + 6H 2O(g) STOICHIOMETRY Practice Problems In your notebook, solve the following problems. SECTION 12.1 THE ARITHMETIC OF EQUATIONS

11 Use the 3-step problem-solving approach you learned in Chapter An apple pie needs 10 large apples, 2 crusts (top and bottom), and 1 tablespoon of cinnamon. Write a balanced equation that fits this situation. How many apples are needed to make 25 pies? 2. Two moles of potassium chloride and three moles of oxygen are produced from the decomposition of two moles of potassium chlorate, KClO3(s). Write the balanced equation. How many moles of oxygen are produced from 12 moles of potassium chlorate? 3. Using the equation from problem 2, how many moles of oxygen are produced from 14 moles of potassium chlorate? 4. Two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water. How many molecules of water are produced from molecules of oxygen? How many moles of water are produced from 22.5 moles of oxygen? SECTION 12.2 CHEMICAL CALCULATIONS 1. Calculate the number of moles of hydrogen chloride produced from 10 moles of hydrogen. H 2(g) + Cl 2(g) 2HCl(g) 2. Calculate the number of moles of chlorine needed to form 14 moles of iron(iii) chloride. 2Fe(s) + 3Cl 2(g) 2FeCl 3(s) 3. Calculate the number of grams of nitrogen dioxide that are produced from 4 moles of nitric oxide. 2NO(g) + O 2(g) 2NO 2(g) 4. Calculate the mass of oxygen produced from the decomposition of 75.0 g of potassium chlorate. 2KClO 3(s) 2KCl(s) + 3O 2(g) 5. Calculate the mass of silver needed to react with chlorine to produce 84 g of silver chloride. (Hint: Write a balanced equation first.) 6. How many liters of carbon monoxide at STP are needed to react with 4.80 g of oxygen gas to produce carbon dioxide? 2CO(g) + O 2(g) 2CO 2(g) 7. Calculate the number of liters of oxygen gas needed to produce 15.0 liters of dinitrogen trioxide. Assume all gases are at the same conditions of temperature and pressure. 2N 2(g) + 3O 2(g) 2N 2O 3(g) acid. Calculate the mass of zinc needed for this reaction. SECTION 12.3 LIMITING REAGENT AND PERCENT YIELD 1. How many moles of water can be made from 4 moles of oxygen gas and 16 moles of hydrogen gas? What is the limiting reagent? 2. Calculate the mass of water produced from the reaction of 24.0 g of H2 and g of O2. What is the limiting reagent? 3. The burning of 18.0 g of carbon produces 55.0 g of carbon dioxide. What is the theoretical yield of CO2? Calculate the percent yield of CO2. 4. Calculate the percent yield of Cl2(g) in the electrolytic decomposition of hydrogen chloride if 25.8 g of HCl produces 13.6 g of chlorine gas.

12 5. One method for reclaiming silver metal from silver chloride results in a 94.6% yield. Calculate the actual mass of silver that can be produced in this reaction if g of silver chloride is converted to silver metal. 2AgCl(s) 2Ag(s) + Cl2(g) 6. What is the actual amount of magnesium oxide produced when excess carbon dioxide reacts with 42.8 g of magnesium metal? The percent yield of MgO(s) for this reaction is 81.7%. 2Mg(s) + CO2(g) 2MgO(s) + C(s) STATES OF MATTER Chapter Quiz Fill in the word(s) that will make each statement true The theory states that the tiny particles in matter are in constant motion Atmospheric pressure 2 with an increase in elevation An increase in the 3 of a substance corresponds to an increase in the average kinetic energy of its particles The energy an object has because of its motion is energy In the kinetic theory, it is assumed that the collisions between gas particles are perfectly Liquids and solids are known as states of matter During evaporation, only those molecules that possess a certain can escape 7 from the surface of a liquid At the boiling point, the vapor pressure of a liquid is equal to the The smallest group of particles in a crystal that retains the shape of a crystal is a(n) A solid that lacks an ordered internal structure is a(n) solid.

13 Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. The change of a substance to vapor is called vaporization. 12. At the triple point, solid, liquid, and gas can exist in equilibrium with one another. 13. A phase diagram shows the temperature and pressure conditions at which a substance exists as a solid, liquid, and gas or vapor. STATES OF MATTER Chapter Test A A. Matching Match each description in Column B with the correct term in Column A. Write the letter of the correct description on the line. Column A 1. amorphous 8. sublimation 2. unit cell 9. boiling point 3. crystal 10. kinetic theory 4. normal boiling point 11. allotrope 5. barometer 12. vapor pressure 6. atmospheric pressure 13. evaporation 7. melting point 14. vacuum

14 Column B a. an empty space with no particles of matter b. the temperature at which a solid changes into a liquid h. a measure of the force exerted by a gas above a liquid i. describes a solid that lacks an ordered internal structure j. the temperature at which a liquid boils at a pressure of kpa c. a device used to measure atmospheric pressure d. the pressure resulting from the collision of particles in air with objects e. the temperature at which the vapor pressure of a liquid is equal to the external pressure k. one of two or more different molecular forms of the same element in the same physical state l. the conversion of a liquid to a gas or vapor at a temperature below the boiling point m. states that the tiny particles in all forms of matter are in constant motion f. the smallest group of particles within a crystal that retains the shape of the crystal n. the change of a solid to a vapor without passing through the liquid state g. a solid in which the particles are arranged in an orderly, repeating, three-dimensional pattern B. Multiple Choice Choose the best answer and write its letter on the line. 15. The average kinetic energy of water molecules is greatest in a. steam at 200 C. c. liquid water at 373 K. b. liquid water at 90 C. d. ice at 0 C. 16. According to the kinetic theory of gases, a. the particles in a gas move rapidly. b. the particles in a gas are relatively far apart. c. the particles in a gas move independently of each other. d. all of the above are true. 17. The temperature at which the motion of particles theoretically ceases is a. 0 C. c. 273 K. b. 273 C. d. 0 K. 18. The average kinetic energy of particles of a substance

15 a. is not affected by the temperature of the substance. b. increases as the temperature of the substance decreases. c. is directly proportional to the temperature of a substance. d. is equal to Which of these statements is not true, according to kinetic theory? a. There is no attraction between particles of a gas. b. Only particles of matter in the gaseous state are in constant motion. c. The particles of a gas collide with each other and with other objects. d. All collisions between particles of gas are perfectly elastic. 20. Standard conditions when working with gases are defined as a. 0 K and kilopascals. c. 0 C and kilopascals. b. 0 K and 1 mm Hg. d. 0 C and 1 mm Hg. 21. The pressure of a gas in a container is 76 mm Hg. This is equivalent to a. 0.1 atm. c. 0.2 atm. b. 1 atm. d atm. 22. A phase diagram gives information on a. volumes of gases. b. conditions at which a substance exists as a solid, liquid, and gas. c. volumes of liquids and solids. d. changes in mass of solids, liquids, and gases. 23. An increase in the temperature of a contained liquid a. causes the vapor pressure above the liquid to increase. b. decreases the vapor pressure above a liquid. c. causes fewer particles to escape the surface of the liquid. d. has no effect on the kinetic energy of the liquid. 24. Water could be made to boil at 105 C by a. applying a great deal of energy. b. increasing the air pressure above the water. c. heating the water more gradually. d. decreasing the air pressure above the water. 25. The direct change of a substance from a solid to a vapor is called:

16 a. evaporation c. condensation. b. sublimation. d. vaporization. 26. Most solids a. are amorphous. b. lack an orderly internal structure. c. are dense and not easily compressed. d. have low melting points. 27. The escape of molecules from the surface of an uncontained liquid is a. boiling. c. evaporation. b. sublimation. d. condensation. C. True-False Classify each of these statements as always true, AT, sometimes true, ST, or never true, NT. 28. The rates of evaporation and condensation are equal at equilibrium. 29. The kinetic energy of all the particles in a given sample of matter is the same. 30. The average kinetic energy of all the molecules in liquid water at 80 C is the same as the average inetic energy of the molecules in oxygen gas at 80 C. 31. Heating a liquid will increase the temperature of the liquid. 32. The melting point and freezing point of a substance are the same. D. Problems Solve the following problems in the space provided. Show your work. 33. A gas is at a pressure of 3.70 atm. What is this pressure in kilopascals? 34. What is the pressure of the gas in problem 33, expressed in millimeters of mercury? E. Essay Write a short essay for the following.

17 35. Explain why the temperature of a gas does not depend on the number of particles in the sample of gas. F. Additional Problems Solve the following problems in the space provided. Show your work. 36. A gas has a pressure of mm Hg. What is the pressure in atmospheres? 37. What is the pressure of the gas in problem 36, expressed in kilopascals? G. Additional Questions Answer the following questions in the space provided. 38. A 100-g sample of water is heated from 50 C to 100 C. At 100 C, although the water is still being heated, the temperature of the water does not rise. Explain why. 39. Some types of bacteria are killed by being heated to a temperature of 150 C for 30 minutes. Explain why water heated under pressure can be used to kill these bacteria, although boiling water at atmospheric pressure does not kill them. STATES OF MATTER Chapter Test B A. Matching Match each term in Column B to the correct description in Column A. Write the letter of the correct term on the line. Column A 1. an instrument used to measure atmospheric pressure 2. a measure of the force exerted by a gas above a liquid 3. The tiny particles in all forms of matter are in constant motion. 4. the temperature at which a solid changes into a liquid

18 5. the pressure required to support 760 mm of Hg at 25 C 6. the change of a substance from a solid to a gas or vapor without passing through the liquid state 7. the SI unit of pressure 8. the conversion of a liquid to a gas or vapor at a temperature below the liquid s boiling point 9. describes the only conditions of temperature and pressure at which all three phases of a substance can exist in equilibrium 10. the pressure that results from the collisions of particles in air with objects 11. the temperature at which a liquid boils at a pressure of kpa 12. the smallest group of particles within a crystal that retains the geometric shape of the crystal 13. the energy an object has because of its motion 14. two or more different molecular forms of the same element in the same physical state

19 Column B a. normal boiling point b. pascal c. kinetic energy d. standard atmosphere e. melting point f. triple point g. evaporation h. kinetic theory i. allotropes j. barometer k. sublimation l. atmospheric pressure m. unit cell n. vapor pressure

20 B. Multiple Choice Choose the best answer and write its letter on the line. 15. According to the kinetic theory, gases consist of particles that a. occupy considerable volume. b. are relatively close together. c. exert attractive and repulsive forces on other particles. d. have motion that is constant, random, and rapid. 16. As you climb a mountain, atmospheric pressure: a. increases. c. remains the same. b. decreases. d. varies randomly. 17. Which of the following is true about atmospheric pressure? a. It is measured with a hydrometer. b. It varies widely, depending on the weather. c. It increases with altitude. d. It affects the boiling point of a liquid. 18. At sea level in fair weather, atmospheric pressure is equal to a kpa. c. 760 mm Hg. b. 1 standard atmosphere. d. all of the above 19. STP refers to: a. 100 C and 1 atm. c. 0 C and 1 atm. b. 0 C and 1 kpa. d. 100 C and 760 mm Hg. 20. A pressure of 2.5 atm is equivalent to a. 41 kpa. c mm Hg. b mm Hg. d. 2.5 kpa. 21. Absolute zero is a. the temperature at which the motion of particles theoretically ceases. b. defined as 0 C. c. the triple point for water. d. all of the above

21 22. At 80 K, the particles of a gas have a. twice the average kinetic energy of the same particles at 40 K. b. half the average kinetic energy of the same particles at 40 K. c. one fourth the average kinetic energy of the same particles at 20 K. d. none of the above 23. Compared with gases, liquids: a. have stronger intermolecular attractions. b. have more space between their particles. c. are much less dense. d. are more easily compressed. 24. Evaporation is a type of a. boiling. c. sublimation. b. vaporization. d. condensation. 25. A decrease in the temperature of a contained liquid causes a. an increase in the vapor pressure. b. a decrease in the vapor pressure. c. more particles to evaporate. d. an increase in the average kinetic energy of the particles. 26. Water could be made to boil at 92 C by a. lowering the external air pressure. b. raising the external air pressure. c. increasing the pressure on the water. d. none of the above 27. In comparison with liquids and gases, solids are a. more dense. c. less organized. b. more easily compressed. d. more likely to flow. 28. Diamond and graphite are examples of a. phases. c. allotropes. b. amorphous solids. d. glasses. 29. The conditions at which the solid, liquid, and gaseous phases of a substance can exist in equilibrium with one another is called

22 a. boiling point. c. sublimation point. b. freezing point. d. triple point. 30. Sublimation can occur because solids have a. a melting point. c. a boiling point. b. a vapor pressure. d. a triple point. C. True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 31. In an elastic collision, kinetic energy is transferred from one particle to another, but the total kinetic energy remains constant. 32. Atmospheric pressure is kpa. 33. The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles in that substance. 34. At any given temperature, the particles of all substances have the same average kinetic energy. 35. The temperature of a boiling liquid can rise above its boiling point. 36. Water boils at 100 C. 37. The melting and freezing points of a substance are the same temperature. D. Essay Write a short essay for the following. 38. Distinguish between the boiling point and the normal boiling point of a liquid. Explain the impact of a change in atmospheric pressure on the relationship between the boiling point and the normal boiling point. E. Additional Questions Answer the following questions in the space provided. 39. Distinguish between gases, liquids, and solids in terms of the kinetic theory.

23 40. Explain why each of the following is true. a. The temperature of a boiling liquid never rises above its boiling point. b. The temperature of an ice and water mixture at 1 standard atmosphere remains at 0 C as long as both ice and liquid water are present, no matter what the surrounding temperature. STATES OF MATTER Practice Problems In your notebook, answer the following questions or solve the following problems. SECTION 13.1 THE NATURE OF GASES 1. Explain why there is no gas pressure inside a vacuum. 2. How would the reading on a barometer change if you were to take one on a trip from Los Angeles to Lake Tahoe, which is at a much higher altitude? 3. The height of a column of mercury in a barometer is mm. What is the atmospheric pressure in atm? In kpa? 4. How does the average kinetic energy of the helium atoms in a balloon change as the helium gas is heated from 100.0ºC to 73ºC? SECTION 13.2 THE NATURE OF LIQUIDS 1. In general, how do the intermolecular attractions between particles in a gas compare with those between particles in a liquid? 2. An open beaker is about half filled with water. How can a dynamic equilibrium be established between the water and the vapor forming above its surface? 3. Explain how the following description is an analogy for evaporative cooling: If the fastest runner is removed from a race, the average speed of the remaining runners will be lower. 4. The normal boiling point of ethanol is 78.5ºC. The normal boiling point of water is 100ºC. At 75ºC, which liquid, ethanol or water, has the greater vapor pressure? Explain. SECTION 13.3 THE NATURE OF SOLIDS 1. How does the crystalline structure of graphite compare with that of diamond? 2. Why is diamond classified as an allotrope of carbon?

24 3. Peanut brittle is a candy that is poured out while hot onto a surface. It is allowed to cool and harden into a sheet, which easily breaks into irregularly shaped pieces. The sugar in peanut brittle solidifies without reforming its crystal lattice. What type of solid is peanut brittle? 4. Which type of solid is likely to have the lowest melting point an ionic solid or a molecular solid? Explain. 5. Give an example of a crystalline solid. What is a crystal? SECTION 13.4 CHANGES OF STATE To answer the following questions, refer to the phase diagram shown in Figure of your textbook. 1. How does the melting point of water change as the pressure increases? 2. What does the line separating the solid phase from the vapor phase represent? 3. What does the line separating the liquid phase from the vapor phase represent? 4. What is the vapor pressure of liquid water at 100ºC?