7. Gases

A container with a movable piston contains 2.0 moles of argon gas. When the volume of the container is 1.5 L, the pressure is 2.4 atm. Calculate the pressure of the container when the piston is raised to give a volume of 2.5 L. Assume the temperature remains constant.

A balloon is filled with 1.5 moles of helium at room temperature, 25℃, and has a volume of 2.4 L. Calculate the volume of the balloon when it is placed into liquid nitrogen at −196℃. Assume that the pressure remains constant.

Which of the following statements about an ideal gas is false?

Under which of the following conditions is a gas least likely to be ideal?

Assuming that chlorine gas behaves as a real gas, what pressure would 1.000 mol would the gas exert in 22.41 L at 273.2 K?

At 273 K and 1 atm pressure, 1 mol of an ideal gas occupies 22.4 L. (Section 10.4) (b) Looking at Figure 18.1, we see that the temperature is lower at 85 km altitude than at 50 km. Does this mean that one mole of an ideal gas would occupy less volume at 85 km than at 50 km? Explain.

Many laboratory gases are sold in steel cylinders with a volume of 43.8 L. What is the mass in grams of argon inside a cylinder whose pressure is 17,180 kPa at 20 °C? (LO 10.4) (a) 1.83 * 107 g (b) 1.81 * 105 g (c) 1.23 * 104 g (d) 122 g

Air pollution in the Mexico City metropolitan area is among the worst in the world. The concentration of ozone in Mexico City has been measured at 441 ppb (0.441 ppm). Mexico City sits at an altitude of 7400 feet, which means its atmospheric pressure is only 0.67 atm. (b) How many ozone molecules are in 1.0 L of air in Mexico City? Assume T = 25 °C.

Complete the following table for an ideal gas: P V n T 101.33 kPa ? L 3.333 mol 300 K

(b) The adult blue whale has a lung capacity of 5.0 * 103 L. Calculate the mass of air (assume an average molar mass of 28.98 g>mol) contained in an adult blue whale's lungs at 0.0 °C and 101.33 kPa, assuming the air behaves ideally.

(a) Calculate the number of molecules in a deep breath of air whose volume is 2.25 L at body temperature, 37 °C, and a pressure of 97.99 kPa.

What volume is occupied by 0.118 mol of helium gas at a pressure of 0.97 atm and a temperature of 305 K?

(b) Carbon dioxide makes up approximately 0.04% of Earth's atmosphere. If you collect a 2.0-L sample from the atmosphere at sea level (101.33 kPa) on a warm day 127 °C2, how many CO2 molecules are in your sample?

What volume is occupied by 12.5 g of argon gas at a pressure of 1.05 atm and a temperature of 322 K? Would the volume be different if the sample were 12.5 g of helium (under identical conditions)?

(a) If the pressure exerted by ozone, O3, in the stratosphere is 304 Pa and the temperature is 250 K, how many ozone molecules are in a liter?

A scuba diver's tank contains 2.50 kg of O2 compressed into a volume of 11.0 L. (b) What volume would this oxygen occupy at 25 °C and 101.33 kPa?

An aerosol spray can with a volume of 125 mL contains 1.30 g of propane gas (C3H8) as a propellant. (c) The can's label says that exposure to temperatures above 50 °C may cause the can to burst. What is the pressure in the can at this temperature?

An aerosol spray can with a volume of 125 mL contains 1.30 g of propane gas (C3H8) as a propellant. (a) If the can is at 25 °C, what is the pressure in the can?

What is the pressure in a 15.0-L cylinder filled with 32.7 g of oxygen gas at a temperature of 302 K?

A 50.0 g sample of solid CO2 (dry ice) is added at -100 °C to an evacuated (all of the gas removed) container with a volume of 5.0 L. If the container is sealed and then allowed to warm to room temperature 125 °C2 so that the entire solid CO2 is converted to a gas, what is the pressure inside the container?

A 334-mL cylinder for use in chemistry lectures contains 5.225 g of helium at 23 °C. How many grams of helium must be released to reduce the pressure to 7.60 MPa assuming ideal gas behavior?

What is the temperature of 0.52 mol of gas at a pressure of 1.3 atm and a volume of 11.8 L?

In an experiment reported in the scientific literature, male cockroaches were made to run at different speeds on a miniature treadmill while their oxygen consumption was measured. In 30 minutes the average cockroach (running at 0.08 km/h) consumed 1.0 mL of O2 at 101.33 kPa pressure and 20 °C per gram of insect mass. (a) How many moles of O2 would be consumed in 1 day by a 6.3-g cockroach moving at this speed?

A piece of dry ice (solid carbon dioxide) with a mass of 28.8 g sublimes (converts from solid to gas) into a large balloon. Assuming that all of the carbon dioxide ends up in the balloon, what is the volume of the balloon at 22 °C and a pressure of 742 mmHg?

If 15.0 g of CO2 gas has a volume of 0.30 L at 300 K, what is its pressure in millimeters of mercury?

If 2.00 g of N2 gas has a volume of 0.40 L and a pressure of 6.0 atm, what is its Kelvin temperature?

Dry ice (solid CO2) has occasionally been used as an 'explosive' in mining. A hole is drilled, dry ice and a small amount of gunpowder are placed in the hole, a fuse is added, and the hole is plugged. When lit, the exploding gunpowder rapidly vaporizes the dry ice, building up an immense pressure. Assume that 500.0 g of dry ice is placed in a cavity with a volume of 0.800 L and the ignited gunpowder heats the CO2 to 700 K. What is the final pressure inside the hole?

The reaction of sodium peroxide 1Na2O22 with CO2 is used in space vehicles to remove CO2 from the air and generate O2 for breathing: 2 Na2O21s2 + 2 CO21g2¡2 Na2CO31s2 + O21g2 (a) Assuming that air is breathed at an average rate of 4.50 L/min (25 °C; 735 mm Hg) and that the concentration of CO2 in expelled air is 3.4% by volume, how many grams of CO2 are produced in 24 h?

A typical high-pressure tire on a bicycle might have a volume of 365 mL and a pressure of 7.80 atm at 25 °C. Suppose the rider filled the tire with helium to minimize weight. What is the mass of the helium in the tire?

As shown in Table 15.2, the equilibrium constant for the reaction N21g2 + 3 H21g2 Δ 2 NH31g2 is Kp = 4.34 * 10-3 at 300 C. Pure NH3 is placed in a 1.00-L flask and allowed to reach equilibrium at this temperature. There are 1.05 g NH3 in the equilibrium mixture. (b) What was the initial mass of ammonia placed in the vessel?

The vapor pressure of water at 25 °C is 23.76 torr. If 1.25 g of water is enclosed in a 1.5-L container, will any liquid be present? If so, what mass of liquid?

The vapor pressure of CCl3F at 300 K is 856 torr. If 11.5 g of CCl3F is enclosed in a 1.0-L container, will any liquid be present? If so, what mass of liquid?

Natural gas is a mixture of hydrocarbons, primarily methane 1CH42 and ethane 1C2H62. A typical mixture might have Xmethane = 0.915 and Xethane = 0.085. Let's assume that we have a 15.50 g sample of natural gas in a volume of 15.00 L at a temperature of 20.00 °C. (b) What is the pressure of the sample in atmospheres?

Air conditioners not only cool air, but dry it as well. A room in a home measures 6.0 m * 10.0 m * 2.2 m. If the outdoor temperature is 30 °C and the partial pressure of water in the air is 85% of the vapor pressure of water at this temperature, what mass of water must be removed from the air each time the volume of air in the room is cycled through the air conditioner? (Assume that all of the water must be removed from the air.) The vapor pressure for water at 30 °C is 31.8 torr.

A sealed flask contains 0.55 g of water at 28 °C. The vapor pressure of water at this temperature is 28.35 mmHg. What is the minimum volume of the flask in order that no liquid water be present in the flask?

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?

The relative humidity of air equals the ratio of the par- tial pressure of water in the air to the equilibrium vapor pressure of water at the same temperature times 100%. If the relative humidity of the air is 58% and its temperature is 68 °F, how many molecules of water are present in a room measuring12ft * 10ft * 8ft?

Carbon dioxide, which is recognized as the major contributor to global warming as a 'greenhouse gas,' is formed when fossil fuels are combusted, as in electrical power plants fueled by coal, oil, or natural gas. One potential way to reduce the amount of CO2 added to the atmosphere is to store it as a compressed gas in underground formations. Consider a 1000-megawatt coal-fired power plant that produces about 6 * 106 tons of CO2 per year. (a) Assuming ideal-gas behavior, 101.3 kPa, and 27 C, calculate the volume of CO2 produced by this power plant.

Nickel carbonyl, Ni1CO24, is one of the most toxic substances known. The present maximum allowable concentration in laboratory air during an 8-hr workday is 1 ppb (parts per billion) by volume, which means that there is one mole of Ni1CO24 for every 109 moles of gas. Assume 24 C and 101.3 kPa pressure. What mass of Ni1CO24 is allowable in a laboratory room that is 3.5 m * 6.0 m * 2.5 m?

Olympic cyclists fill their tires with helium to make them lighter. Calculate the mass of air in an air-filled tire and the mass of helium in a helium-filled tire. Assume that the volume of the tire is 855 mL, that it is filled to a total pressure of 125 psi, and that the temperature is 25 °C. Also, assume an average molar mass for air of 28.8 g>mol. Calculate the mass of helium in a helium-filled tire.

Olympic cyclists fill their tires with helium to make them lighter. Calculate the mass of air in an air-filled tire and the mass of helium in a helium-filled tire. Assume that the volume of the tire is 855 mL, that it is filled to a total pressure of 125 psi, and that the temperature is 25 °C. Also, assume an average molar mass for air of 28.8 g>mol. What is the mass difference between the two?

Olympic cyclists fill their tires with helium to make them lighter. Calculate the mass of air in an air-filled tire and the mass of helium in a helium-filled tire. Assume that the volume of the tire is 855 mL, that it is filled to a total pressure of 125 psi, and that the temperature is 25 °C. Also, assume an average molar mass for air of 28.8 g>mol. Calculate the mass of air in an air-filled tire.

The reaction NO1g2 + NO21g2 ∆ N2O31g2 takes place in the atmosphere with Kc = 13 at 298 K. A gas mixture is prepared with 2.0 mol NO and 3.0 mol NO2 and an initial total pressure of 1.65 atm. (b) What is the volume of the container?

The radius of a xenon atom is 1.3 * 10 - 8 cm. A 100-mL flask is filled with Xe at a pressure of 1.0 atm and a temperature of 273 K. Calculate the fraction of the volume that is occupied by Xe atoms. (Hint: The atoms are spheres.)

A driver with a nearly empty fuel tank may say she is 'running on fumes.' If a 15.0-gallon automobile gas tank had only gasoline vapor remaining in it, what is the farthest the vehicle could travel if it gets 20.0 miles per gallon on liquid gasoline? Assume the average molar mass of molecules in gasoline is 105 g/mol, the density of liquid gasoline is 0.75 g/mL, the pressure is 743 mm Hg, and the temperature is 25 °C.

Assume that you take a flask, evacuate it to remove all the air, and find its mass to be 478.1 g. You then fill the flask with argon to a pressure of 2.15 atm and reweigh it. What would the balance read in grams if the flask has a volume of 7.35 L and the temperature is 20.0 °C?

The apparatus shown consists of three temperature-jacketed 1.000-L bulbs connected by stopcocks. Bulb A contains a mixture of H2O1g2, CO21g2, and N21g2 at 25 °C and a total pressure of 564 mm Hg. Bulb B is empty and is held at a temperature of -70 °C. Bulb C is also empty and is held at a temperature of -190 °C. The stopcocks are closed, and the volume of the lines connecting the bulbs is zero. CO2 sublimes at -78 °C, and N2 boils at -196 °C.

(b) How many moles of H2O are in the system?

When solid mercury(I) carbonate, Hg2CO3, is added to nitric acid, HNO3, a reaction occurs to give mercury(II) nitrate, Hg1NO322, water, and two gases A and B: Hg2CO31s2 + HNO31aq2¡ Hg1NO3221aq2 + H2O1l 2 + A1g2 + B1g2 (a) When the gases are placed in a 500.0-mL bulb at 20 °C, the pressure is 258 mm Hg. How many moles of gas are present?

Would the volume be different if the gas was argon (under the same conditions)?

What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?