Question

A 0.10 M solution of formic acid (HCOOH) is prepared in various solvents:

a. pure water

b. 0.10 M NaHCOO solution,

c. 0.10 M Ca(HCOO)2 solution, and

d. 0.10 M NaCl.

Compute the pH of each solution. The Ka of formic acid is 1.78 x 10

Answer 1

$a)pH=1/2(pK_a-log(c_0))=2.38pH$

$b)pH=pK_a+log\left(\frac{c(NaHCOO)}{c(HCOOH)}\right)=pK_a=3.75pH$

$c) pH=pK_a+log\left(\frac{2c(Ca(HCOO)_2)}{c(HCOOH)}\right)=pK_a+log(2)=4.05pH$

$d) pH =2.38$