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Exam 3B
Spring 2004

March 26, 2004


Possibly useful information:

pH = –log[ H3O+ ]

pOH = –log[ OH ]

pH + pOH = 14.00 at 25 oC

Kc = KaKb/Kw

KaKb = Kw (for a conjugate acid/base pair)

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

Acid

Ka (25 oC)

pKa

HClO

2.9×10–8

7.54

HCN

6.2×10–10

9.21

H3AsO4

6.0×10–3

2.22

H2AsO4

1.0×10–7

7.00

HAsO42–

3.2×10–12

11.49

HOCN

3.5×10–4

3.46

Salt

Ksp (25 oC)

 

BaF2

1.0×10–6

 

CaSO4

9.1×10–6

 

Pb(OH)2

1.2×10–15

 


1. Complete and balance the following reactions:

a. H2SO4(aq) + CsOH(aq)

b. CH3CH2NH2(aq) + H2O(l)

c. H3AsO4(aq) + H2O(l)

d. Cu(NO3)2(aq) + Li2S(aq)

e. HClO(aq) + CN(aq)

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

g. Ni(ClO4)2(aq) + NaOH(aq)

2. For each of the following salts, indicate if an aqueous solution will be acidic, basic, or neutral. If the salt is not neutral, write the reaction that determines the acidity or basicity.

a. KBr

b. Fe(ClO4)3

c. Na2CrO4

3. A solution is made that is 1.0 mM NaH2AsO4 and 1.0 mM Na2HAsO4 at 25 oC.

a. Estimate the pH of the solution.

b. Estimate the pH of the solution after 0.010 mmol of NaOH is added to 1.0 L of the solution.

c. Estimate the pH of the solution after 0.10 mol of NaOH is added to 1.0 L of the solution.

4. Estimate the molar solubility of lead hydroxide in pure water at 25 oC.