Practice Problems for Chapter 10
1. The Venusian atmosphere is approximately 65% CO2 and 35% N2 at a pressure of 90 atm. Assuming that the percentages of CO2 and N2 are equivalent to the mole fractions, what are the partial pressures of CO2 and N2?
2. Two flasks of ammonia gas and hydrogen fluoride gas are attached to opposite ends of a tube 10.00 cm long. The flasks are opened and the gases are allowed to diffuse and react.
a) At what point along the tube (expressed as cm from one end) will the gases meet?
b) Write a balanced chemical equation for the reaction of ammonia gas and hydrogen fluoride gas.
c) If the flask containing ammonia holds 2.0 L and the original pressure of ammonia was 800 torr at 20°C, how many moles of ammonia were present before reaction?
3. A compound has the empirical formula of CHCl. A 256 mL flask at 100°C and 750 torr has this gaseous compound present at a density of 3.125 g/L. What are the molecular weight and the molecular formula of this compound?
4. Urea is used extensively as a source of nitrogen in fertilizers. It is present naturally in bird droppings ('guano'), but the commercial production involves reaction of ammonia and carbon dioxide according the equation below. Ammonia is added to an evacuated 5.0 L flask until the pressure is 9.0 atm at 23°C, then carbon dioxide is added to give final pressure of 14.0 atm. The flask is heated to 100°C.
2 NH3 (g) + CO2 (g) ---> H2NC(O)NH2 (s) + H2O (g)
a) Assuming 100% reaction, what mass of urea is formed? Specify the limiting agent.
b) What is the pressure of water vapor at the end of the reaction?
5. A 2.0 L container is filled with an ideal gas to a pressure of 40.0 atm at 0.0°C.
a) How many moles of gas is present?
b) What is the pressure inside the container when the temperature is raised to 45°C?
6. At STP, 1.0 L of gaseous Br2 reacts completely with 3.0 L of gaseous F2, producing 2.0 L of a gaseous product. What is the formula of the product?