Chem122 Midterm 1

NO books, lecture notes, cell-phones, PDAs, laptops, talking.

For Multiple Choice Problems (on the back) - Circle your answer to each question BELOW.

If more than one answer is circled for a question no credit will be given for it.

1. [ out of 16 pts ] A mixture of gases contains 66.0 g CO2, 2.02 g of H2, and 16.0 g of O2. If the total pressure of the mixture is 725 torr, what is the partial pressure of each gas?

[ do not neglect significant figures! ] SHOW YOUR WORK to get full credit.

1) Number of moles:

2) Pressure of each gas:

2. [ out of 16 pts ] When 11.1 g of lead reacts with 3.81 L of oxygen gas, measured at 1.00 atm and 25.0°C, 11.8 kJ of heat is released at constant pressure. What is ∆H° for this reaction?
(R = 0.0821 L • atm/(K • mol)) 2Pb(s) + O2(g) → 2PbO(s)

[ do not neglect significant figures! ] SHOW YOUR WORK to get full credit.

1) Determine the limiting reactant:

2) Figuring out ΔH°:

If in doubt, show all the relevant work to get partial credit for the multiple-choice questions.

3. [ 12 pts ] What volume of nitrous oxide gas, N2O, has the same number of atoms as 9.00 L of neon gas at the same temperature and pressure?

a) 36.0 L

b) 9.00 L

c) 3.00 L

d) 2.25 L

e) 27.0 L

4. [ 12 pts ] The heat required to raise the temperature of 55.85 g of iron by 1°C is called its

a) entropy.

b) specific heat.

c) heat of fusion.

d) heat of vaporization.

e) molar heat capacity.

5. [ 12 pts ] Which of the following gases will have the slowest rate of effusion at constant temperature?
a) CF4
b) F2
c) H2
d) Ne
e) SO3

6. [ 12 pts ] All of the following statements are true for an exothermic reaction except
a) The temperature of the reaction system increases.
b) The temperature of the surroundings increases.
c) Heat passes from the reaction system to the surroundings.
d) The products