HOMEWORK 11-1 (pp )

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1 CHAPTER 11 HOMEWORK 11-1 (pp ) VOCABULARY Define. 1. Gay-Lussac s law of combining volumes of gases 2. Avogadro s law Answer each question. 3. Write and explain the equation that expresses the relationship between gas volume and number of moles, according to Avogadro s law. 4. What do the coefficients in a chemical reaction involving gases indicate? GRAPHIC ORGANIZER Using an additional sheet of paper, make a K-W-L Chart similar to the one below to record your ideas about the composition of gases. In the K column, write what you already know. In the W column, write what you want to know. Finally, in the L column, record the answers to your questions as you read. You may not be able to answer all of your questions. Continue working on your K-W-L chart as you read the rest of Chapter 11. The Composition of Gases K W L What I Know What I Want to Know What I ve Learned 1. Which statement is true? a. According to Avogadro s law, gas volume is inversely proportional to the number of moles of gas. b. Reactant elements are always in monatomic form when they combine to form products. c. The coefficients in a chemical reaction indicate the relative masses of the gases involved. d. At room temperature, all of the elements that are gases (except noble gases) exist as diatomic molecules. 2. Given the equation CH 4 + 2O 2 2H 2 + CO 2, how many liters of carbon dioxide are formed from 3.0 L of oxygen? a. 0.5 L b. 1.0 L c. 1.5 L d. 4.0 L

2 CHAPTER 11 HOMEWORK 11-2 (pp ) VOCABULARY Write true or false. 1. The standard molar volume of a gas is the volume occupied by one liter of gas at standard temperature and pressure. 2. The standard molar volume of a gas is 22.4 L. 3. In addition to having a standard molar volume, all gases have a standard molar mass. 4. Avogadro s law applies to solids, liquids, and gases. 5. The mercury barometer was invented by Robert Boyle. Solve. 1. A chemical reaction produces mol of ethane, C 2 H 6. What volume in liters is occupied by this gas sample at STP? 2. At STP, what is the volume of 4.05 mol of H 2 O(g)? 3. A chemical reaction produced ml of nitrogen monoxide gas at STP. What was the mass in grams of the gas produced? 4. What is the mass of 58.7 L of carbon dioxide gas at STP? 5. What is the volume of 56.5 g of helium gas at STP? 1. What is the volume of 99.4 g of sulfur trioxide gas at STP? a L b x 10 3 L c L d x 10 3 L 2. Suppose that you have two 22.4-L containers, one containing helium gas and the other containing nitrogen gas. Which statement about the containers is not true? a. Each container holds the same number of molecules. b. The mass of the gases in each container is identical. c. Each container holds one mole of its respective gas. d. All of the statements are true.

3 CHAPTER 11 HOMEWORK 11-3 (pp ) VOCABULARY AND Write and explain the proportion that represents each gas law. Gas Law Proportion Boyle s law Charles s law Avogadro s law Write the equation that reflects the ideal gas law. Explain the variables. On a separate sheet of paper, show how to reduce the ideal gas law to Boyle s law, Charles s law, Gay-Lussac s law, and Avogadro s law by holding some of the variables constant. 1. In a sample held at constant volume and temperature, if the number of molecules is increased, then a. the collision rate decreases. b. the collision rate increases. c. the pressure increases. d. both b and c are true. 2. The constant R has the same value for a. all gases. b. all noble gases. c. all gases whose behavior approaches that of ideal gases. d. any gases that act according to Avogadro s law and Charles s law.

4 CHAPTER 11 HOMEWORK 11-4 (pp ) VOCABULARY Select the unit in Column B that represents the variable in Column A. Column A Column B 1. P a. L 2. V b. L atm/(mol K) 3. T c. mol 4. R d. atm 5. n e. K GRAPHIC ORGANIZER Each row of the chart contains data about a gas sample. Fill in the information that is missing in each row. Mass (g) Volume (L) Pressure (atm) Temperature ( C) Molar Mass (g/mol) The density of a gas varies a. directly with molar mass and Kelvin temperature and inversely with pressure. b. directly with molar mass, Kelvin temperature, and pressure. c. directly with pressure and inversely with molar mass and Kelvin temperature. d. directly with molar mass and pressure and inversely with Kelvin temperature. 2. A sample that contains 6.25 mol of gas at 22.0 C has a pressure of 680 mm Hg. What is the volume of the gas? a L b L c L d L

5 CHAPTER 11 HOMEWORK 11-5 (pp ) Answer each question. 1. How do chemical reactions show volume ratios of gases? 2. Explain how to find the volume of a gaseous product given the volume of a gaseous reactant in a chemical equation. 3. Suppose a chemical reaction involves gaseous reactants and both solid and gas products. Can volumevolume ratios be used to determine the amount of gaseous product? Explain why or why not. ANOTHER Complete the problems. 1. Assume that methane and oxygen gas combine according to the following equation: CH 4 + 2O 2 2H 2 + CO 2. If 3.20 mol of methane are used in the reaction, what volume of hydrogen gas is produced? What volume of carbon dioxide is produced? 2. Different amounts of methane and oxygen can combine according to this equation: 2CH O 2 8CO H 2 O. If 2.0 L of methane are used in the reaction, what volume of O 2 must be used to make the reaction go to completion? How many moles of carbon dioxide are produced? 3. If 4.80 mol of H 2 are used as one of the reactants in the reaction N 2 + 3H 2 2NH 3, what volume of NH 3 will result? 1. Assume that hydrochloric acid and oxygen react according to the following equation: HCl + O 2 Cl 2 + H 2 O. If mol of O 2 are used, what is the volume of chlorine gas produced? a. 1.2 L b c L d. The problem cannot be solved. 2. Given the equation 2NH 3 (g) + 2Na(s) 2NaNH 2 (s) + H 2 (g), assume that 2 mol of Na are used. What is the volume of hydrogen gas produced by the reaction? a. 1 L b L c L d. The problem cannot be solved.

6 CHAPTER 11 HOMEWORK 11-6 (pp ) VOCABULARY AND 1. Given the volume of a reacting gas, explain how to calculate the volume of another gaseous reactant or product. What conditions must be met to use this method? 2. Given the volume of a reactant or product gas, explain how to calculate the mass of a second reactant or product. 3. If you know the mass of a substance, how can you calculate the volume of a gaseous product or reactant? Solve. 1. Considering the equation 2C 2 H 6 + 7O 2 4CO 2 + 6H 2 O, what mass of oxygen gas must be use to produce 4.20 L of carbon dioxide at STP? 2. Considering the equation C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O, how many grams of carbon dioxide gas are produced if 2.40 L of oxygen gas are used? L of C 3 H 8 are used as a reactant in the following chemical reaction: C 3 H 8 + 5O 2 3CO 2 + 4H 2 O. How many grams of oxygen gas are used? How many moles of carbon dioxide are produced? L F 2 are used in the reaction represented by the following equation: U(s) + 3F 2 (g) UF 6 (g). What is the mass of UF 6 produced? a g b g c g d. 107 g 2. Given the chemical reaction C 8 H 8 (s) + 10O 2 (g) 8CO 2 (g) + 4H 2 O(g), how many grams of oxygen gas are needed to produce 9.80 L of carbon dioxide gas? a g b g c g d g