Question

What volume of 6 M HCl and 2 M HCl should be mixed to get two litre of 3 M HCl?

• A. $\text{0.5 L of 6 M HCl and 1.5 L of 2 M HCl}$
• B. $\text{1.5 L of 6 M HCl and 0.5 L of 2 M HCl}$
• C. $\text{1 L of 6 M HCl and 1 L of 2 M HCl}$
• D. $\text{0.75 L of 6 M HCl and 1.25 L of 2 M HCl}$

Answer 1

The correct option is A $\text{0.5 L of 6 M HCl and 1.5 L of 2 M HCl}$

$\text{Let, the volume of 6 M HCl required to obtain 2 L of 3 M HCl = x L}$
$\therefore \text{Volume of 2 M HCl required}=(2-x)L$
$\begin{array}{ccccc}{M}_1{V}_1& +& M_2{V}_2& =& M_3{V}_3\\ 6MHCl& & 2MHCl& & 3MHCl\end{array}$
$6\left(x\right)+2(2-x)=3\times 2$
$\Rightarrow 6x+4-2x=6\Rightarrow 4x=2$
$\therefore x=0.5L$
Hence, volume of 6 M HCl required = 0.5 L
Volume of 2 M HCl required = 1.5 L