##### Exam 2B Spring 2004

February 27, 2004

Possibly useful information:

 pH = –log[ H3O+ ] pOH = –log[ OH– ] pH + pOH = 14.00 at 25 oC log(1.0×10–3) = –3 log(1.0×10–4) = –4 log(2.0×10–3) = –2.698970004 log(2.0×10–4) = –3.696870004 log(3.0×10–3) = –2.522878745 log(3.0×10–4) = –3.522878745 log(4.0×10–3) = –2.397940009 log(4.0×10–4) = –3.397940009 log(5.0×10–3) = –2.301029996 log(5.0×10–4) = –3.301029996 log(6.0×10–3) = –2.22184875 log(6.0×10–4) = –3.22184875 log(7.0×10–3) = –2.15490196 log(7.0×10–4) = –3.15490196 log(8.0×10–3) = –2.096910013 log(8.0×10–4) = –3.096910013 log(9.0×10–3) = –2.045757491 log(9.0×10–4) = –3.045757491

1. Complete and balance the following reactions:

a. H2SO4(aq) + KOH(aq)

b. C6H5NH2(aq) + HBr(aq)

c. HOBr(aq) + H2O(l)

d. Mg(OH)2(s) + HNO3(aq)

2. Complete and balance the following reaction and identify the acid, the base, the conjugate acid, and the conjugate base:

CO32–(aq) + CH3CH2CO2H(aq)

3. Identify the Lewis acid and the Lewis base in the following reaction.

Al(OH)3(s) + OH(aq) Al(OH)4(aq)

4. Identify the stronger acid in pair given below. Briefly (5 words or less) justify your reasoning.

a. H2O or H2S

b. H2SeO4 or H2TeO4

5. Calculate the pH and pOH of the following solutions:

a. 2.0×10–4 M perchloric acid.

b. 2.0×10–4 M potassium hydroxide.

c. 3.0×10–4 M calcium hydroxide.

6. Consider the reaction shown below, which has H = 131 kJ/mol.

C(s) + H2O(g) CO(g) + H2(g)

a. Which way will the reaction shift if the pressure is decreased by expanding the volume?

b. Which way will the reaction shift if the temperature is lowered?

7. Estimate the pH of a 2.0×10–4 M solution of HNO2. Show all the steps needed to solve the problem until you are required to do algebra. Then make a chemically reasonable estimate of the pH. Ka = 7.2×10–4