Chapter 6

Consider the reaction: $$ 2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{SO}_{3}(g) $$ a. If \(285.5 \mathrm{~mL}\) of \(\mathrm{SO}_{2}\) reacts with \(158.9 \mathrm{~mL}\) of \(\mathrm{O}_{2}\) (both measured at \(315 \mathrm{~K}\) and \(50.0 \mathrm{mmHg}\) ), what is the limiting reactant and the theoretical yield of \(\mathrm{SO}_{3} ?\) b. If \(187.2 \mathrm{~mL}\) of \(\mathrm{SO}_{3}\) is collected (measured at \(315 \mathrm{~K}\) and \(50.0 \mathrm{mmHg}\) ), what is the percent yield for the reaction?

In a common classroom demonstration, a balloon is filled with air and drenched with liquid nitrogen. The balloon contracts as the gases within the balloon cool. Suppose a balloon initially contains \(2.95 \mathrm{~L}\) of air at a temperature of \(25.0^{\circ} \mathrm{C}\) and a pressure of 0.998 atm. Calculate the expected volume of the balloon upon cooling to \(-196^{\circ} \mathrm{C}\) (the boiling point of liquid nitrogen). When the demonstration is carried out, the actual volume of the balloon decreases to 0.61 L. How does the observed volume of the balloon compare to your calculated value? Explain the difference.

An ordinary gasoline can measuring \(30.0 \mathrm{~cm}\) by \(20.0 \mathrm{~cm}\) by \(15.0 \mathrm{~cm}\) is evacuated with a vacuum pump. Assuming that virtually all of the air can be removed from inside the can and that atmospheric pressure is 14.7 psi, what is the total force (in pounds) on the surface of the can? Do you think that the can could withstand the force?

A 160.0 -L helium tank contains pure helium at a pressure of 1855 psi and a temperature of 298 K. How many 3.5 -L helium balloons will the helium in the tank fill? (Assume an atmospheric pressure of 1.0 atm and a temperature of 298 K.)

The radius of a xenon atom is \(1.3 \times 10^{-8} \mathrm{~cm} .\) A \(100-\mathrm{mL}\) 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 mixture of \(8.0 \mathrm{~g} \mathrm{CH}_{4}\) and \(8.0 \mathrm{~g}\) Xe is placed in a container, and the total pressure is found to be 0.44 atm. Determine the partial pressure of \(\mathrm{CH}_{4}\)

A gas mixture contains \(75.2 \%\) nitrogen and \(24.8 \%\) krypton by mass. What is the partial pressure of krypton in the mixture if the total pressure is \(745 \mathrm{mmHg}\) ?

Two identical balloons are filled to the same volume, one with air and one with helium. The next day, the volume of the airfilled balloon has decreased by \(5.0 \% .\) By what percent has the volume of the helium-filled balloon decreased? (Assume that the air is four-fifths nitrogen and one-fifth oxygen and that the temperature did not change.)

Exactly equal amounts (in moles) of gas A and gas B are combined in a 1 -L container at room temperature. Gas \(\mathrm{B}\) has a molar mass that is twice that of gas A. Which statement is true for the mixture of gases and why? a. The molecules of gas \(\mathrm{B}\) have greater kinetic energy than those of gas A. b. Gas \(\mathrm{B}\) has a greater partial pressure than gas \(\mathrm{A}\). c. The molecules of gas \(\mathrm{B}\) have a greater average velocity than those of gas \(\mathrm{A}\). d. Gas B makes a greater contribution to the average density of the mixture than gas A.

The volume of a sample of a fixed amount of gas is decreased from \(2.0 \mathrm{~L}\) to \(1.0 \mathrm{~L}\). The temperature of the gas in kelvins is then doubled. What is the final pressure of the gas in terms of the initial pressure?

Which gas sample has the greatest volume at STP? a. \(10.0 \mathrm{~g} \mathrm{Kr}\) b. \(10.0 \mathrm{~g}\) Xe c. \(10.0 \mathrm{~g}\) He

Review the ideal gas law. Without referring back to the text, use algebra to write the ideal gas law and solve for each of the individual variables it contains. Have each group member solve for a different variable and present answers to the group.

Calculate the pressure exerted by 1 mol of an ideal gas in a box that is \(0.500 \mathrm{~L}\) and \(298 \mathrm{~K}\). Have each group member calculate the pressure of \(1 \mathrm{~mol}\) of the following gases in the same box at the same temperature: He, Ne, \(\mathrm{H}_{2}, \mathrm{CH}_{4},\) and \(\mathrm{CO}_{2} .\) Compare group members' answers as well as all answers with the pressure of an ideal gas. Assuming that the van der Waals equation predictions are accurate, account for why the pressure of each gas is higher or lower than that predicted for an ideal gas.