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Exam 3A
Spring 2005

April 15, 2005


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

Cr(OH)3

6.3×10–31

[Ag(EDTA)]3–

2.1×107

H3PO4

7.1×10–3

Fe(OH)2

8.0×10–16

[Fe(EDTA)]2–

2.1×1014

H2PO4

6.3×10–8

Fe(OH)3

4×10–38

[Fe(EDTA)]

1.7×1024

HPO42–

4.2×10–13

PbBr2

4.0×10–5

[Pb(OH)3]

3.8×1014

H2S

1.0×10–7

AgC2H3O2

2.0×10–3

[Cr(OH)4]

8×1029

HS

1×10–19

CaC2O4

2.7×10–9

 

 

 

 

 

 

 

 

Substance

Hfo
kJ/mol

So
J/mol•K

 

 

HCl(g)

–92

187

 

 

HCl(aq)

–167

56

 

 

H2O(g)

–242

189

 

 

H2O(l)

–286

70.

 

 

H3O+(aq)

–286

70.

 

 

Cl(g)

–234

153

 

 

Cl(aq)

–167

56

 

 

NO3(aq)

–205

146

 

 

Ag+(aq)

106

73

 

 

AgCl(s)

–127

96

 

 

AgNO3(s)

–124

141

 

 


1. Complete and balance the following reactions:

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

b. CH3CH2NH2(aq) + H2O(l)

c. Ag+(aq) + EDTA4–(aq)

d. Mn(NO3)2(aq) + Na2S(aq)

e. Hydrogen phosphate ion plus chlorite ion

f. Ti2+(aq) + H2O(l)

g. Cu(CH3CO2)(aq) + HCl(aq)

2. Identify if the following ionic salts are acidic or basic in aqueous solution. Show the reaction that defines the acidity or basicity.

a. NaHSO4

b. Fe(NO3)2

c. Mg(IO3)2

3. A buffer is prepared to be 0.10 M in H2S and 0.10 M in NaHS.

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

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

4. Will the solubility in water increase, decrease, or stay the same for the following salts if they are added to a pH = 14 solution? Briefly explain your answer.

a. CaC2O4

b. Cr(OH)3

5. Determine the solubility of lead(II) bromide in a buffer with pH = 11.0.

6. Calculate Ho and So for the reaction of solid silver nitrate with aqueous hydrochloric acid.