Question

to neutralise 20 mL of M/10 NaOH, the volume of M/20 HCl needed is?

Answer 1

1/10 x 20 = 1/20 x V
so V = 40 ml

Answer 2

The required formula is V₁ X S₁ = V₂ X S₂

Where V is volume of acid or base and S is strength of respective solution.

Given, V₁ = 20 ml (volume of base)

S₁ = M/10 (strength of base)

S₂ = M/20 (strength of acid)

Therefore, V₂ = (V₁S₁) / S₂

or, V₂ = [20 X (M/10)] / (M/20)

or, V₂ = 40

Thus the volume of M/20 HCl required to neutralise 20 ml of M/10 NaOH is 40 ml.