Exam 5: Gases and the Kinetic-Molecular Theory

Dry air is approximately 78% nitrogen, 21% oxygen, and 1% argon, by number of molecules. What is the partial pressure of oxygen in a sample of dry air, if atmospheric pressure is 751 torr?

A 255-mL gas sample weighing 0.292 g is at 52810 Pa and 127°C. a. How many moles of gas are present? b. What is the molar mass of the gas?

A 750-mL sample of hydrogen exerts a pressure of 822 torr at 325 K. What pressure does it exert if the temperature is raised to 475 K at constant volume?

A sample container of carbon monoxide occupies a volume of 435 mL at a pressure of 785 torr and a temperature of 298 K. What would its temperature be if the volume were changed to 265 mL at a pressure of 785 torr?

Magnesium metal (0.100 mol) and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to completion. How many liters of hydrogen gas, measured at STP, are produced? Mg(s) + 2HCl(aq)  MgCl₂(aq) + H₂(g)

A sample of nitrogen gas at 298 K and 745 torr has a volume of 37.42 L. What volume will it occupy if the pressure is increased to 894 torr at constant temperature?

Calculate the rms speed of carbon dioxide molecules at STP.

The pressure of hydrogen sulfide gas in a container is 35,650 Pa. What is this pressure in torr?

A 1.00-L sample of a pure gas weighs 0.785 g and is at 0.965 atm and 29.2°C. a. What is the molar mass of the gas? b. If the volume and temperature are kept constant while 0.400 g of the same gas are added to that already in the container, what will the new pressure be?

Arrange the following gases in order of increasing rate of effusion. C₂H₆ Ar HCl PH₃

Which of the lines on the figure below is the best representation of the relationship between the volume of a gas and its pressure, other factors remaining constant?

Methane, CH₄(g), reacts with steam to give synthesis gas, a mixture of carbon monoxide and hydrogen, which is used as starting material for the synthesis of a number of organic and inorganic compounds. CH₄(g) + H₂O(g)  CO(g) + H₂(g) [unbalanced] What mass of hydrogen is formed if 275 L of methane (measured at STP) is converted to synthesis gas?

What is the density of carbon dioxide gas at -25.2°C and 98.0 kPa?

For real gases, PV < nRT, always.

A sample of oxygen gas has its absolute temperature halved while the pressure of the gas remained constant. If the initial volume is 400 mL, what is the final volume?

Select the statement which does NOT apply to an ideal gas.

Hydrogen gas exerts a pressure of 466 torr in a container. What is this pressure in atmospheres?

Chlorofluorocarbons are important air pollutants implicated in global warming and ozone depletion. How fast does the chlorofluorocarbon CF₂Cl₂ diffuse relative to N₂, the main component of the atmosphere? In other words, calculate the ratio of diffusion rates:

A gas mixture, with a total pressure of 300. torr, consists of equal masses of Ne (atomic weight 20.) and Ar (atomic weight 40.). What is the partial pressure of Ar, in torr?

A gas consists of 85.7 % carbon and 14.3 % hydrogen, by weight. A sample of this gas weighing 0.673 g occupies 729 mL at a pressure of 720.0 mmHg and a temperature of 77°C. Calculate its empirical and molecular formulas.