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How many litres of water must be added to 2 litre aqueous solution of HCl with a pH of 1 to create an aqueous solution with pH of 2 ?

How many litres of water must be added to 2 litre aqueous solution of HCl with a pH of 1 to create an aqueous solution with pH of 2 ? Correct Answer 18 L

pH = 1  ⇒          = 10–1 = 0.1 M

pH = 2 ⇒          = 10–2 = 0.01 M

for dilution of HCl  M1V1 = M2V2 

0.1 × 2 = 0.01 × V2 

V2 = 20 L

Volume of water added = 20 – 2 = 18 litre 

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