Question

The molarity of nitrous acid at which its pH becomes
2.(K = 4.5 x 10-4) :-
(1) 0.3333
(2) 0.4444
(3) 0.6666
(4) 0.2222​

Answer 1

Dear Student,

◆ Answer - (4)

[HNO₂] = 0.2222 mol/L

● Explaination -

Hydronium ion concentration in solution is calculated by -

pH = -log[H₃O+]

2 = -log[H₃O+]

[H₃O+] = antilog(-2)

[H₃O+] = 10⁻² mol/L

Dissociation of nitric acid in water is represented by -

HNO₂ + H₂O --> H₃O+ + NO₂-

So now,

K = [H₃O+].[NO₂-] / [HNO₂]

4.5×10⁻⁴ = 10⁻² × 10⁻² / [HNO₂]

[HNO₂] = 10⁻⁴ / (4.5×10⁻⁴)

[HNO₂] = 1/4.5

[HNO₂] = 0.2222 mol/L

Therefore, molarity of nitrous acid is 0.2222 mol/L.

Hope this helps you...

Answer 2

Answer:

Option 4

Explanation:

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