Question

How many moles of $HCI$ will be present in $100mL$ of a solution of specific gravity $1.08$, containing $20\%$ $HCI$ by mass?

• A. $0.50$
• B. $0.60$
• C. $0.80$
• D. $0.12$

Answer 1

Answer: (B)

$0.60$

Given density in specific gravity of $HCl=1.08$

As $20\%$ of $HCl$ is present by mass

In $100ml$ solution $20\%$ of it contain $HCl$ by mass

$20\%$ of $100ml=20ml$

$20ml$ of solution has $m$ mass of $HCl$, with specific gravity $=108$

Thus $m=1.08\times 20ml=21.6g$

Mass of $HCl$ present in $100$ml of solution is $21.6g$

Thus moles of $HCl$ $=\frac{21.6g}{36.5g/mole}=0.6mole$