Question

11. How much water would I need to add to 200 mL of a 1.4 M KCl solution to bring the molarity to 1 M? (Read question carefully)

Answer 1

Molarity of solution 1 (M1) = 1.4 M ...(given)

Volume of solution 1 (V1) = 200 ml ...(given)

Molarity of solution 2 (M2) = 1 M ....(given)

Volume of solution 2 (V2) = ?

We know, concentration equation is -

M1 V1 = M2V2

So,

1.4 M × 200 ml = 1 M × V2

1.4 M × 200 ml / 1 M = V2

280 ml = V2

This V2 is the final volume of 1M solution.

Initial volume of solution was = 200mL

Amount of water added = 280 - 200 = 80mL

Thus we need to add 80mL of distilled water to 1.4M , 200ml solution to make it 1M .