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 [H⁺]

(i) pH of milk = 6.8

Since, pH = –log [H⁺]

6.8 = –log [H⁺]

log [H⁺] = –6.8

[H⁺] = anitlog(–6.8)

`= 1.5 xx 10^(-7) :M"`

(ii) pH of black coffee = 5.0

Since, pH = –log [H⁺]

5.0 = –log [H⁺]

log [H⁺] = –5.0

[H⁺] = anitlog(–5.0)

= 10^-5 M

(iii) pH of tomato juice = 4.2

Since, pH = –log [H⁺]

4.2 = –log [H⁺]

log [H⁺] = –4.2

[H⁺] = anitlog(–4.2)

`= 6.31 xx 10^(-5)`M

iv) pH of lemon juice = 2.2

Since, pH = –log [H⁺]

2.2 = –log [H⁺]

log [H⁺] = –2.2

[H⁺] = anitlog(–2.2)

`= 6.31 xx 10^(-3)`M

(v) pH of egg white = 7.8

Since, pH = –log [H⁺]

7.8 = –log [H⁺]

log [H⁺] = –7.8

[H⁺] = anitlog(–7.8)

`= 1.58 xx 10^(-8)`M