1. the Surface Temperature of Venus Is About 1050 K, and the Pressure Is About 75 Earth

Unit 6 Challenge Questions

1. The surface temperature of Venus is about 1050 K, and the pressure is about 75 earth atmospheres. Assuming these conditions represent a Venus “STP”, what is the standard molar volume (in liters) of a gas on Venus?

2. 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?

3. What is the total mass (in grams) of oxygen in a room measuring 4.0 m by 5.0 m by 2.5 m? Assume that the gas is at STP and that the air contains 20.95% oxygen by volume.

4. Chemical explosions are characterized by the instantaneous release of large quantities of hot gases, which set up a shock wave of enormous pressure (up to 700,000 atm) and velocity (up to 20,000 mi/hr). For example, explosion of nitroglycerin (C3H5N3O9) releases four gases, A, B, C, and D:

C3H5N3O9 (l)  a A (g) + b B (g) + c C (g) + d D (g) Assume that the explosion of 1 mol (227 g) of nitroglycerin releases gases with a temperature of 1950 C and a volume of 1323 L at 1.00 atm of pressure. a) How many moles of hot gas are released by explosion of 0.00400 mol of nitroglycerin?

b) When the products released by an explosion of 0.00400 mol of nitroglycerin were placed in a 500.0 ml flask and the flask was cooled to -10 C, product A solidified, and the pressure inside the flask was 623 mm Hg. How many moles of A were present, and what is its likely identity?

c) When gases B, C, and D were passed through a tube of powdered Li2O, gas B reacted to form Li2CO3. The remaining gases, C and D, were collected in another 500.0 mL flask and found to have a pressure of 260 mm Hg at 25 C. How many moles of B were present, and what is the likely identity?

d) When gases C and D were passed through a hot tube of powdered copper, gas C reacted to form CuO. The remaining gas, D, was collected in a third 500.0 mL flask and found to have a mass of 0.168 g and a pressure of 223 mm Hg at 25C. How many moles of C and D are present, and what are their likely identities? e) Write a balanced chemical equation for the explosion of nitroglycerin.