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## Gases Chapter 10/11 Modern Chemistry

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**GasesChapter 10/11Modern Chemistry**Sections 10.1, 11.1-11.3 The Kinetic Molecular Theory of Matter Gases and Pressure The Gas Laws Gas Volumes and the Ideal Gas Law Chapter 8 Section 1 Describing Chemical Reactions p. 261-275**Section 11.3**Gas Volumes and the Ideal Gas Law Chapter 11 Section 3 Ideal Gas Law p. 378-385**Comparing Gas Volumes**p. 380 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Law of Combining Volumes**Gay-Lussac’s Law of Combining Volumes of Gas “At constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers.” H2 (g) + O2(g) H2O (g) 2L 1L 2L This could be any volume units. Chapter 11 Section 3 Ideal Gas Law p. 378-385**Combining Volumes of Gases**p. xx Chapter 11 Section 3 Ideal Gas Law p. 378-385**Combining Volumes**p. xx Insert Holt Visualizing Matter Disc 2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Avogadro’s Law**“Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.” 2H2 (g) + O2(g) 2H2O (g) 2 molecules 1 molecule 2 molecules 2 moles 1 mole 2moles 2 volumes 1 volume 2 volumes Chapter 11 Section 3 Ideal Gas Law p. 378-385**Avogadro’s Law**Same volume – Same number of particles The type of gas doesn’t affect this relationship. At STP, one mole of any gas occupies 22.4 L. Chapter 11 Section 3 Ideal Gas Law p. 378-385**Molar Volume**p. 379 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Molar Volume of a Gas**The volume occupied by one mole of gas at STP is know as the standard molar volume of a gas. 22.41410 L / 1 mole 22.4 L / mole Chapter 11 Section 3 Ideal Gas Law p. 378-385**Molar Volume Problems**a. What volume does 0.0685 mol of gas occupy at STP? b. What quantity of gas, in moles, is contained in 2.21 L at STP? p. 381 1. 0.0987 mol Chapter 11 Section 3 Ideal Gas Law p. 378-385**Practice Problems p. 381**• At STP, what is the volume of 7.08 mol of nitrogen gas? • A sample of hydrogen gas occupies 14.1 L at STP. How many moles of the gas are present? p. 381 • 159 L N2 • 2. 0.629 mol H2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Density of Gases at STP**M 44.01 g CO2 For a one mole sample of gas M = molar mass = ________ g V = molar volume = 22.4 L D= = = 1.799 g/L CO2 V 22.4 L CO2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Density**Insert Holt Visualizing Matter Disc 2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Density Problem**• What is the density of C3H8 gas at STP? 1. 1.9684 g/L Chapter 11 Section 3 Ideal Gas Law p. 378-385**Practice Problems**1. 1.251 g/L 2. 0.7156 g/L • What is the density of nitrogen gas at STP? • What is the density of CH4 gas at STP? Great News! We’ve bred a cow that doesn’t release any methane. Chapter 11 Section 3 Ideal Gas Law p. 378-385**atm**kPa mmHg Kelvin liters constant moles Ideal Gas Law • “The mathematical relationship among pressure, volume, temperature and the number of moles of a gas” • Nothing is held constant; one set of conditions. P V = n R T Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ideal Gas Law**Boyle’s Law Charles Law Gay-Lussac’s Law P V R = T n Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ideal Gas Constant p.384**Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ideal Gas Law Problems**• What is the pressure in atmospheres exerted by a 0.500 mol sample of nitrogen gas in a 10.0 L container at 298 K? p. 385 1. 1.22 atm Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ideal Gas Law Problems**An unknown gas has a density of 0.0262 g/mL at a pressure of 0.918 atm and a temperature of 10.°C. What is the molar mass of the gas? p. 898 #289 663 g/mol Chapter 11 Section 3 Ideal Gas Law p. 378-385**Practice Problems p. 385**• What pressure, in atmospheres, is exerted by 0.325 mol of hydrogen gas in a 4.08 L container at 35°C? • A gas sample occupies 8.77 L at 20°C.What is the pressure, in atmospheres, given that there are 1.45 mol of gas in the sample? p. 385 1. 2.01 atm 2. 3.98 atm Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry**• Three new “tools” • Law of Combining Gas Volumes • Use the coefficients (works with gases only) • Molar volume • 22.4 L / 1 mole (works at STP only!) • Ideal Gas Law • PV = nRT • A way to convert from moles to liters if the conditions are not STP Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry**• Propane, C3H8, is a gas that is sometimes used as a fuel for cooking and heating. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) • What will be the volume, in liters, of oxygen required for the complete combustion of 0.350 L of propane? • What will be the volume of carbon dioxide produced in the reaction? Assume that all volume measurements are made at the same temperature and pressure. p. 382 1. (a) 1.75 L O2 (b) 1.05 L CO2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**• Assuming all volume measurements are made at the same temperature and pressure, what volume of hydrogen gas is needed to react completely with 4.55 L of oxygen gas to produce water vapor? p. 382 1. 9.10 L H2 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**Zinc and hydrochloric acid react to produce hydrogen gas. If 5.00 grams of zinc is reacted with excess acid at STP, how many liters of gas will be produced? 1.71 liters Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**Baking soda and vinegar react to produce carbon dioxide gas. If 17.0 grams of baking soda are reacted with excess vinegar, how many liters of carbon dioxide will be produced at STP? NaHCO3(aq)+ HC2H3O2(aq) CO2(g)+ H2O (l)+ NaC2H3O2(aq) 4.53 L Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**In the decomposition of H2O2 solution, water and oxygen form. If the oxygen gas is collected over water at 25.0 C and a total pressure of 92.1 kPa, what volume of gas , in liters, can be expected to form if 18.0 grams of H2O2 are decomposed? 7.38 L Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**How many liters of ozone, O3 can be destroyed at 200. K and 7.00 kPa if 100. grams of chlorine gas reacts according to the following equation. Cl2 + 2O3 2ClO + 2O2 670 L Chapter 11 Section 3 Ideal Gas Law p. 378-385**Gas Stoichiometry Problem**When 2.50 L of C3H8 at STP burns, what total volume of gaseous products is formed? The volume of the products is measured at 175°C and 1.14 atm. C3H8 (g) + 5O2 (g) → 3CO2(g) + 4H2O (g) p. 899 # 311 d. answer Chapter 11 Section 3 Ideal Gas Law p. 378-385**Air Bag Reactions**Insert McMurry Fay Chemistry Disc 1 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ch 11 Sec 3 Homework**Combined and Ideal Gas Law ProblemsPage 897 # 268, 272, 273; Page 898 # 287, 292, 294; Page 899 #300 Chapter 11 Section 3 Ideal Gas Law p. 378-385**Ch 11 Sec 3 Homework**Gas Stoichiometry Problems Page 899 #310a, 312, 314 a-c, 315 Chapter 11 Section 3 Ideal Gas Law p. 378-385