Which is the larger species in each pair?

a. Li o r Li^{+}

b. Cs^{1- }o r Cs^{+ }

c. Cr^{1-} or Cr^{3+}

d. O or O^{2-}

Watch Solution

A quantity of CO gas occupies a volume of 0.48 L at 1.0 atm and 275 K. The pressure of the gas is lowered and its temperature is raised until its volume is 1.3 L. Find the density of the CO under the new conditions.

Watch Solution

A 10-liter container is filled with 0.10 mol of H_{2}(g) and heated to 3000 K causing some of the H_{2}(g) to decompose into H(g). The pressure is found to be 3.0 atm. Find the partial pressure of the H(g) that foms from H_{2} at this temperature. (Assume two significant figures for the temperature.)

Watch Solution

A gas mixture composed of helium and argon has a density of 0.670 g/L at a 755 mmHg and 298 K. What is the composition of the mixture by volume?

Watch Solution

A sample of N_{2}O_{3}(g) has a pressure of 0.017 atm. The temperature (in K) is then doubled and the N_{2}O_{3} undergoes complete decomposition to NO_{2}(g) and NO(g). Find the total pressure of the mixture of gases assuming constant volume and no additional temperature change.

Watch Solution

The radius of a xenon atom is 1.3 X 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.)

Watch Solution

A particular balloon can be stretched to a maximum surface area of 1257 cm ^{2}. The balloon is filled with 3.0 L of helium gas at a pressure of 755 torr and a temperature of 298 K. The balloon is then allowed to rise in the atmosphere. If the atmospheric temperature is 273 K, at what pressure will the balloon burst? (Assume the balloon to be in the shape of a sphere.)

Watch Solution

An 11.5-mL sample of liquid butane (density = 0.573 g/ mL) is evaporated in an otherwise empty container at a temperature of 28.5 °C. The pressure in the container following evaporation is 892 torr. What is the volume of the container?

Watch Solution

Twenty-five milliliters of liquid nitrogen (density = 0.807 g/mL) is poured into a cylindrical container with a radius of 10.0 cm and a length of 20.0 cm. The container initially contains only air at a pressure of 760.0 mmHg (atmospheric pressure) and a temperature of 298 K. If the liquid nitrogen completely vaporizes, what is the total force (in Ib) on the interior of the container at 298 K?

Watch Solution

The emission of NO_{2} by fossiI fuel combustion can be prevented by injecting gaseous urea into the combustion mixture. The urea reduces NO (which oxidizes in air to form NO_{2}) according to the reaction:

2 CO(NH_{2})_{2}(g) + 4 NO(g) + O_{2}(g) → 4 N_{2}(g) + 2 CO_{2}(g) + 4 H_{2}O(g)

Suppose that the exhaust stream of an automobile has a flow rate of 2.55 L/s at 655 K and contains a partial pressure of NO of 12.4 torr. What total mass of urea is necessary to react completely with the NO formed during 8.0 hours of driving?

Watch Solution

In a common classroom demonstration, a balloon is filled with air and submerged in liquid nitrogen. The balloon contracts as the gases within the balloon cool. Suppose the balloon initially contains 2.95 L of air at a temperature of 25.0 °C and a pressure of 0.998 atm. Calculate the expected volume of the balloon upon cooling to -196 °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? Can you explain the difference?

Watch Solution

Ammonium nitrate decomposes explosively upon heating according to the balanced equation:

2 NH_{4}NO_{3}(s) → 2 N_{2}(g) + O_{2}(g) + 4 H_{2}O(g)

Calculate the total volume of gas (at 125 °C and 748 mmHg) produced by the complete decomposition of 1.55 kg of ammonium nitrate.

Watch Solution

Consider the reaction:

2 SO_{2}(g) + O_{2}(g) → 2 SO_{3}(g)

b. If 187.2 mL of SO_{3} is collected (measured at 315 K and 50.0 mmHg), what is the percent yield for the reaction?

Watch Solution

When hydrochloric acid is poured over potassium sulfide, 42.9 mL of hydrogen sulfide gas is produced at a pressure of 752 torr and 25.8 °C. Write an equation for the gas-evolution reaction and determine how much potassium sulfide (in grams) reacted.

Watch Solution

Consider the reaction:

2 Ag_{2}O(s) → 4 Ag(s) + O_{2}(g)

If this reaction produces 15.8 g of Ag(s), what total volume of gas can be collected over water at a temperature of 25 °C and a total pressure of 752 mmHg?

Watch Solution

A gaseous hydrogen and carbon containing compound is decomposed and found to contain 85.63% C and 14.37% H by mass. The mass of 258 mL of the gas, measured at STP, was 0.646 g. What is the molecular formula of the compound?

Watch Solution

A 118-mL flask is evacuated and found to have a mass of 97.129 g. When the flask is filled with 768 torr of helium gas at 35 °C, it has a mass of 97.171 g. Was the helium gas pure?

Watch Solution

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.

Watch Solution

A 2.85-g sample of an unknown chlorofluorocarbon decomposes and produces 564mL of chlorine gas at a pressure of 752mmHg and a temperature of 298 K. What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?

Watch Solution

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 coaling (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) → H_{2}(g) + ZnCl(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.)

Watch Solution

Use the van der Waals equation and the ideal gas equation to calculate the pressure exerted by 1.000 mol of Cl_{2} in a volume of 5.000 L. at a temperature of 273.0 K. Explain why the two values are different.

Watch Solution

Which postulate of the kinetic molecular theory breaks down under conditions of low temperature? Explain.

Watch Solution

Which postulate of the kinetic molecular theory breaks down under conditions of high pressure? Explain.

Watch Solution

The graph shows the distribution of molecular velocities for the same molecule at two different temperatures (T_{1} and T_{2}). Which temperature is greater? Explain.

Watch Solution

A sample of N_{2}O effuses from a container in 42 seconds. How long would it take the same amount of gaseous I_{2} to effuse from the same container under identical conditions?

Watch Solution