Question

You are supplied with 500 ml each of $2N$ $HCl$ and $5N$ $HCl$. What is the maximum volume of $3M$ $HCl$ that you can prepare using only these two solutions?

• A. 250 ml
• B. 500 ml
• C. 750 ml
• D. 1166.7 ml

Answer 1

The correct option is C 750 ml

We have to prepare maximum volume solution of 3 N. (3N is same as 3 M for HCl). Hence, we will take all 500 ml of 2 N solution and $x$ ml of 5 N solution.

Note: For maximum volume, we have to use the lower concentrated solution to get 3 M.

$\therefore 500\times 2+x\times 5=3(x+500)$

$1000+5x=3x+1500$

$2x=500$

$x=250ml$

$\therefore$ Final volume $=500+x$

$=500+250$

$=750$ ml

Hence, option C is correct.