Question

What volume of 5 m hcl and 1 m hcl should be mixed to get one litre of 2 m hcl ? a?

Answer 1

Let us suppose that the volume of 5M HCl (V1) = x L

So, Volume of 1M HCl required to make 1L of 2M HCl (V2) = (1-x) L

Let us take M1 = 5M and M2 = 1M, 

We know that, Molarity of a mixture is given by the equation :

(M1V1 + M2V2) / (V1 + V2) = M3

[5x + 1(1-x)] / 1 = 2

5x - x  + 1 = 2

4x = 1

x = 1/4 = 0.25 L

Therefore, Volume of 5M HCl = 0.25L

and Volume of 1 M HCl = 1-0.25 = 0.75 L