Question

The concentrated sulphuric acid that is peddled commercial is 95% $H_{2}S{O}_4$ by weight. If the density of this commercial acid is $1.834g$ $c{m}^{-3}$, the molarity of this solution is

• A. $17.8M$
• B. $12.0M$
• C. $10.5M$
• D. $15.7M$

Answer 1

Answer: (A)

$95\%H_{2}S{O}_4$ by weight means $100g{H}_{2}S{O}_4$ solution contains $95g{H}_{2}S{O}_4$ by mass. Molar mass of $H_{2}S{O}_4=98gmo{l}^{-1}$
Moles in $95g=\frac{95}{98}=0.969$ mole
Volume of $100g{H}_{2}S{O}_4$
$=\frac{mass}{density}=\frac{100g}{1.834gc{m}^{-3}}$
$=54.52c{m}^3=54.52\times 10^{-}3L$
$Molarity=\frac{Molesofsolute}{VolmeofsolutinL}$
$=\frac{0.969}{54.52\times 10^{-3}}=17.8M$