Problem 80
Consider the chemical reaction: 2 H2O(l) → 2 H2(g) + O2(g) What mass of H2O is required to form 1.85 L of O2 at a temperature of 315 K and a pressure of 0.981 atm?
Problem 81
CH3OH can be synthesized by the reaction: CO(g) + 2 H2(g) → CH3OH( g) What volume of H2 gas (in L), at 748 mmHg and 86 °C, is required to synthesize 25.8 g CH3OH? How many liters of CO gas, measured under the same conditions, are required?
Problem 82
Oxygen gas reacts with powdered aluminum according to the reaction: 4 Al(s) + 3 O2(g) → 2 Al2O3(s) What volume of O2 gas (in L), measured at 782 mmHg and 25 °C, completely reacts with 53.2 g Al?
Problem 83
Automobile air bags inflate following a serious impact. The impact triggers the chemical reaction: 2 NaN3(s) → 2 Na(s) + 3 N2(g) If an automobile air bag has a volume of 11.8 L, what mass of NaN3 (in g) is required to fully inflate the air bag upon impact? Assume STP conditions.
Problem 84
Lithium reacts with nitrogen gas according to the reaction: 6 Li(s) + N2(g) → 2 Li3N(s) What mass of lithium (in g) reacts completely with 58.5 mL of N2 gas at STP?
Problem 85
Hydrogen gas (a potential future fuel) can be formed by the reaction of methane with water according to the equation: CH4(g) + H2O(g) → CO(g) + 3 H2(g) In a particular reaction, 25.5 L of methane gas (measured at a pressure of 732 torr and a temperature of 25 °C) mixes with 22.8 L of water vapor (measured at a pressure of 702 torr and a temperature of 125 °C). The reaction produces 26.2 L of hydrogen gas at STP. What is the percent yield of the reaction?
Problem 86
Ozone is depleted in the stratosphere by chlorine from CF3Cl according to this set of equations:
CF3Cl + UV light → CF3 + Cl
Cl + O3 → ClO + O2
O3 + UV light → O2 + O
ClO + O → Cl + O2
What total volume of ozone at a pressure of 25.0 mmHg and a temperature of 225 K is destroyed when all of the chlorine from 15.0 g of CF3Cl goes through 10 cycles of the given reactions?
Problem 87
Chlorine gas reacts with fluorine gas to form chlorine trifluoride. Cl2(g) + 3 F2(g) → 2 ClF3(g) A 2.00-L reaction vessel, initially at 298 K, contains chlorine gas at a partial pressure of 337 mmHg and fluorine gas at a partial pressure of 729 mmHg. Identify the limiting reactant. Determine the theoretical yield of ClF3 in grams.
Problem 88
Carbon monoxide gas reacts with hydrogen gas to form methanol. CO(g) + 2 H2(g) → CH3OH(g) A 1.50-L reaction vessel, initially at 305 K, contains carbon monoxide gas at a partial pressure of 232 mmHg and hydrogen gas at a partial pressure of 397 mmHg. Identify the limiting reactant. Determine the theoretical yield of methanol in grams.
Problem 89
Consider a 1.0-L sample of helium gas and a 1.0-L sample of argon gas, both at room temperature and atmospheric pressure. a. Do the atoms in the helium sample have the same average kinetic energy as the atoms in the argon sample?
Problem 90a
A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon. a. Which of the two gases exerts the greater partial pressure?
Problem 90c
A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon. c. The molecules of which gas have the greater average kinetic energy?
Problem 91a
Calculate the root mean square velocity of F2, Cl2, and Br2 at 298 K.
Problem 91b
Calculate the kinetic energy of F2, Cl2, and Br2 at 298 K.
Problem 91c
Calculate the root mean square velocity and kinetic energy of F2, Cl2, and Br2 at 298 K. Rank these three halogens with respect to their rate of effusion.
Problem 92
Calculate the root mean square velocity and kinetic energy of CO, CO2, and SO3 at 298 K. Which gas has the greatest velocity? The greatest kinetic energy? The greatest effusion rate?
Problem 93
We separate U-235 from U-238 by fluorinating a sample of uranium to form UF6 (which is a gas) and then taking advantage of the different rates of effusion and diffusion for compounds containing the two isotopes. Calculate the ratio of effusion rates for 238UF6 and 235UF6. The atomic mass of U-235 is 235.054 amu and that of U-238 is 238.051 amu.
Problem 94
Calculate the ratio of effusion rates for Ar and Kr.
Problem 95
A sample of argon effuses from a container in 112 seconds. The same amount of an unknown noble gas requires 79.6 seconds. Identify the second gas.
Problem 96
A sample of CO2 effuses from a container in 55 seconds. How long will it take the same amount of gaseous Xe to effuse from the same container under identical conditions?
Problem 97
The graph shows the distribution of molecular velocities for two different molecules (A and B) at the same temperature. Which molecule has the higher molar mass? Which molecule has the higher rate of effusion?
Problem 98
The graph shows the distribution of molecular velocities for the same molecule at two different temperatures (T1 and T2). Which temperature is greater? Explain.
Problem 99
Which postulate of the kinetic molecular theory breaks down under conditions of high pressure? Explain.
Problem 101
Use the van der Waals equation and the ideal gas equation to calculate the volume of 1.000 mol of neon at a pressure of 500.0 atm and a temperature of 355.0 K. Explain why the two values are different. (Hint: One way to solve the van der Waals equation for V is to use successive approximations. Use the ideal gas law to get a preliminary estimate for V.)
Problem 102
Use the van der Waals equation and the ideal gas equation to calculate the pressure exerted by 1.000 mol of Cl2 in a volume of 5.000 L at a temperature of 273.0 K. Explain why the two values are different.
Problem 105
Modern pennies are composed of zinc coated with copper. A student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coating (to expose the underlying zinc). The student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the HCl (the copper remains undissolved): Zn(s) + 2 HCl(aq)¡ H2( g) + ZnCl2(aq) The student collects the hydrogen produced over water at 25 °C. The collected gas occupies a volume of 0.899 L at a total pressure of 791 mmHg. Calculate the percent zinc (by mass) in the penny. (Assume that all the Zn in the penny dissolves.)
Problem 106
A 2.85-g sample of an unknown chlorofluorocarbon decomposes and produces 564 mL of chlorine gas at a pressure of 752 mmHg and a temperature of 298 K. What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?
Problem 107
The mass of an evacuated 255 mL flask is 143.187 g. The mass of the flask filled with 267 torr of an unknown gas at 25 °C is 143.289 g. Calculate the molar mass of the unknown gas.
- When a 118-mL flask is evacuated, it has a mass of 97.129 g. Upon filling it with 768 torr of helium gas at 35 °C, the mass increases to 97.171 g. Based on this information, can we determine if the helium gas was pure?
Problem 108
Problem 109
A gaseous hydrogen- and carbon-containing compound is decomposed and found to contain 82.66% carbon and 17.34% hydrogen by mass. The mass of 158 mL of the gas, measured at 556 mmHg and 25 °C, was 0.275 g. What is the molecular formula of the compound?
Ch.6 - Gases