Question

prepare 250 ml of 5n HCL from the given 12n HCL

Answer 1

NaVa=NbVb
250×5=12×Vb
Vb=250×5/12
1250/12=Vb
Vb=104.16

Answer 2

Given: To prepare 250 ml of 5N HCl from 12N HCl,(commercial grade)

The amount of 12N HCl required to make 250ml of 5N HCl, is calculated by using normality equation as follows,

N_1V_1 = N_2V_2

where, N_1 = Normality of concentrated acid HCl = 12 N

Volume of concentrated acid required = V_1

Normality of dilute acid to be prepared N_2 = 5 N

Volume of dilute acid to be prepared V_2 = 250 ml

By substituting in the above equation we get.

$12\times V1\quad =\quad 5\times 250$

$V1\quad =\quad 5\times \frac { 250 }{ 12 }$

= 104.2ml

Therefore 104.2 ml of concentrated Hydrochloric acid is required to make 250 ml of 5N HCl (Which made up with distilled water.To avoid interference of other ions).