Question

Hydrolic acid solution A and B have concentration of 0.5 N and 0.1N respectively. The volume of solutions A and B required to make 2 litres of 0.2 N hydrochloric are
A. 0.5 L of A + 1.5 L of B
B. 1.5 L of A + 0.5 L of B
C. 1.0 L of A + 1.0 L of B
D. 0.75 L of A + 1.25 L of B

Answer 1

Correct Answer - A
Let volume of A = xL
Volume of B = (2-x)L
`because M_(1)V_(1)+M_(2)V_(2)=M(V_(1)+V_(2))`
`rArr 0.5x +0.1(2-x)=0.2(x+2-x)`
(`because` for HCl, 0.1 M HCl = 0.1 N HCl)
`rArr 0.5 x + 0.2 =0.4 rArr 0.4 x = 0.2`
`therefore x =(0.2)/(0.4)=0.5 L`
Since x = 0.5 L (vol. of A), then
2 - x = 2 - 0.5 = 1.5 L (Vol. of B).