or
pH = -log[Ka] + log$\frac{[A^-]}{[HA]}$
Read the problem and list out the values given.
Step 2 :
Substitute the values in the corresponding formula to obtain the pH value.
pH = -log[Ka] + log$\frac{[A^-]}{[HA]}$
To mimic a blood buffer, a scientist prepared 1.000L buffer containing 0.0025mol carbonic acid and 0.025mol hydrogen carbonate ion. Calculate the pH of the buffer. The Ka of carbonic acid is 4.2 $\times$ 10-7.
Step 1 :Given data
Ka = 4.2 $\times$ 10-7
[A-] = 0.025
[HA] = 0.0025
Step 2 :Substitute the values in the formula.
pH = -log[Ka] + log$\frac{[A^-]}{[HA]}$
pH = -log[4.2 $\times$ 10-7] + log$\frac{0.025}{0.0025}$
pH = 7.207
Answer :The answer is pH = 7.207
Calculate the pH of blood containing 0.0025M HPO42- and 0.0015M H2PO4-. Ka of H2PO4- = 6.2 $\times$ 10-8.
Step 1 :Given data
Ka = 6.2 $\times$ 10-8
[A-] = 0.0025
[HA] = 0.0015
Step 2 :Substitute the values in the formula.
pH = -log[Ka] + log$\frac{[A^-]}{[HA]}$
pH = -log[6.2 $\times$ 10-8] + log$\frac{[0.0025]}{[0.0015]}$
pH = 7.42
Answer :The answer is pH = 7.42