Arkansas State University Department of Chemistry and Physics

1. What is Charles’ Law? (4 points)

2. What is the pressure of 0.75 mol of gas at 22^oC in a 3.2 L flask?   (6 points)

3. A student collects a sample of gas at 1.07 atm and 36^oC which occupies a volume of 1.5 L, calculate its volume at STP.   (6 points)

4. A gas with a density of 0.626 is placed in 1.5 L flask at  25^oC.  If the pressure of the gas is 0.899 atm, what is the molecular mass of this gas?  (10 points)

5. A mixture of Ar and CO gases is collected over water at 28^oC and an atmospheric pressure of 1.0 atm.  If the partial pressure of Ar is 570 torr, what is the partial pressure of CO?  (vapor pressure of water at 28^oC is 28.3 mmHg)             (6 points)

6. Determine the partial pressures of each of the gases in the following mixture: 85.20 g N₂,  10.09 g Ar and 32.00 g O₂.  The gases are at 2.5 atm of pressure.  (12 points)

7. State the kinetic molecular theory.            (10 points)

8. A piece of potassium metal undergoes complete reaction with water as follows:

 2 K (s)  +   2 H₂O (l)  ------->   2 KOH (aq)  +   H₂ (g)

 The hydrogen gas is collected over water at 25 ^oC.  The volume of gas is 752 mL measured at 0.95 atm.  Calculate the number of grams of K used in the reaction.  (vapor pressure of water = 0.0313 atm)     (12 points)
 

9. Calculate the volume of 5.7 g SO₂ at STP. (8 points)

10. Give van der Waals’ Equation of State.   What do the variables a and b tell us?       (6 points)

11. Explain why the rates of effusion are inversely proportional to molar mass?  Which gas would effuse quicker, He or Cl₂? (8 points)
12. What is the pressure in torr of 2 mol of a gas occupying a volume of 500 mL at 27^oC? (4 points)

13. If you increase the temperature of a gas, what happens to the volume if the moles and pressure is kept constant.    (4 points)

14. State Guy-Lussac’s Law.  (4 points)

BONUS (4 points) What is meant by absolute zero? Be brief.