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 × 10-7 M

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(ii) pH of black coffee = 5.0
Since, pH =-log [H+]
5.0 = -log [H+]
log [H+]= -5.0 [H+] = anitlog(-5.0) = 10-5M

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(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 × 10-5M

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(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 × 10-3M

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(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 × 10-8M