Question

The pH of milk, black coffee, tomato juice, lemon juice and egg white are 6.8, 5.0, 4.2, 2.2 and 7.8 respectively. Calculate corresponding hydrogen ion concentration in each.

Answer 1

The hydrogen ion concentration in the given substances can be calculated by using the given relation: $pH=–log\left[H^{+}\right]$
(i) pH of milk = 6.8
Since, $pH=–log\left[H^{+}\right]6.8=–log\left[H^{+}\right]log\left[H^{+}\right]=–6.8\left[H^{+}\right]=anitlog(–6.8)=1.5\times {10}^{-7}M$

(ii) pH of black coffee = 5.0
Since, $pH=–log\left[H^{+}\right]5.0=–log\left[H^{+}\right]log\left[H^{+}\right]=–5.0\left[H^{+}\right]=anitlog(–5.0)={10}^{-5}M$

(iii) pH of tomato juice = 4.2
Since, $pH=–log\left[H^{+}\right]4.2=–log\left[H^{+}\right]log\left[H^{+}\right]=–4.2\left[H^{+}\right]=anitlog(–4.2)=6.31\times {10}^{-5}M$

(iv) pH of lemon juice = 2.2
Since, $pH=–log\left[H^{+}\right]2.2=–log\left[H^{+}\right]log\left[H^{+}\right]=–2.2\left[H^{+}\right]=anitlog(–2.2)=6.31\times {10}^{-3}M$

(v) pH of egg white = 7.8
Since, $pH=–log\left[H^{+}\right]7.8=–log\left[H^{+}\right]log\left[H^{+}\right]=–7.8\left[H^{+}\right]=anitlog(–7.8)=1.58\times {10}^{-8}M$