Question

The molarity of a solution obtained by mixing $800\, mL$ of $0.5\, M HCl$ with $200\, mL$ of $1\, M\, HCl$ will be

• A. 0.8 M
• B. 0.6 M
• C. 0.4 M
• D. 0.2 M

Answer 1

Answer: (B)

Given,
$: M_{1}=0.5 M , M_{2}=1 \,M , $
$V_{1}=800 \,mL , V_{2}=200 \,mL$
$V_{3}=V_{1}+V_{2}=800+200=1000 \,mL$
$M_{1}\, V_{1}+M_{2} \,V_{2}=M_{3} \,V_{3}$
$\Rightarrow 0.5 \times 800+1 \times 200=M_{3} \times 1000$
$M_{3}=\frac{0.5 \times 800+1 \times 200}{1000}$
$=\frac{600}{1000}=0.6 \,M$