Problem: Which weak acid would be best to use when preparing a buffer solution with a pH of 8.20? a) An acid with Ka = 1.0 x10-3 M b) An acid with Ka = 1.0x1O-6 M c) An acid with Ka = 1.3x10-5 M d) An acid with Ka = 6.6 x10-9 M e) An acid with Ka = 4.0 X 10-10 M f) An acid with Ka = 7.9 X 10-5 M

FREE Expert Solution

maximum buffering capacity:              pH = pKa

buffering range:              pH = pKa ± 1


pKa = -log Ka


a) 

pKa = -log(1.0×10-3) = 3.00

buffering range: 2.oo to 4.00


b) 

pKa = -log(1.0×10-6) = 6.00

buffering range: 5.00 to 7.00


c) 

pKa = -log(1.3×10-5) = 4.87

buffering range: 3.87 to 5.87


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Problem Details

Which weak acid would be best to use when preparing a buffer solution with a pH of 8.20? 

a) An acid with Ka = 1.0 x10-3 

b) An acid with K= 1.0x1O-6

c) An acid with Ka = 1.3x10-5

d) An acid with Ka = 6.6 x10-9

e) An acid with Ka = 4.0 X 10-10

f) An acid with Ka = 7.9 X 10-5 M