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Exam 3A
Spring 2006

No electronic devices (calculators, PDAs, laptop computers, cell phones, iPods, MP3 players, etc.) are allowed for this exam.

Read all questions carefully. Numerical answers require units to obtain full credit. Answers without work shown will receive no credit. Remember to balance all chemical equations.

Possibly useful information:

pH = –log[ H3O+ ]

pOH = –log[ OH ]

pH + pOH = 14.00 at 25 oC

Kc = Ka(acid)/Ka(conjugate acid)

Acid

Ka

Salt

Ksp

Complex ion

Kf

HClO2

1.1×10–2

Co(OH)3

1.6×10–44

[Ag(EDTA)]3–

2.1×107

HOCN

3.5×10–4

Cd(OH)2

2.5×10–14

[Fe(EDTA)]2–

2.1×1014

NH4+

5.6×10–10

Li3PO4

3.2×10–9

[Fe(EDTA)]

1.7×1024

HCN

6.2×10–10

ScF3

4.2×10–18

[Cd(NH3)4]2+

1.3×107

   

   

[Co(NH3)6]3+

4.5×1033


1. Complete and balance the following reactions:

a. H2SO4(aq) + KOH(aq)

b. thiocyanate ion plus water

c. Fe2+(aq) + EDTA4–(aq)

d. CoCl2(aq) + Na2CO3(aq)

e. HOCN(aq) + NH3(aq)

f. Mn2+(aq) + H2O(l)

g. Ba(OH)2(s) + H3PO4(aq)

2. Identify if the following ionic salts are acidic, basic, or neutral in aqueous solution. Show the reaction that defines the acidity or basicity, if the salt is not neutral.

a. Cu(ClO4)2

b. KClO3

c. NaNO3

3. A buffer is prepared to be 0.10 M in HClO2 and 0.10 M in NaClO2.

a. Estimate the pH of the solution, showing all of your work.

b. 0.1 g of HCl(g) is added to 1 L of the buffer. Estimate the new pH. Do not do any detailed calculations.

4. A mixture of Cd(OH)2 in water is prepared. Will the solubility in increase, decrease, or stay the same if the mixture is added to the following solutions. Show a chemical reaction to justify your answer if the solubility increases or decreases.

a. 1 M HNO3

b. 1 M NaNO3

c. 1 M NH3

5. Determine the solubility of Li3PO4 in a 0.10 M solution of LiNO3.