Question

$31.5g$ of $HN{O}_3$ is added to $500mL$ of water. Then choose the correct option(s):

• A. $\text{Strength of the solution is}31.5g{L}^{-1}$
• B. $\text{Molarity=1 M}$
• C. $\text{Molarity=1.5 M}$
• D. $\text{Strength of the solution is}63g{L}^{-1}$

Answer 1

Answer: (B), (D)

$\text{Strength of the solution is}63g{L}^{-1}$

$\text{Molecular Mass of}HN{O}_3=1+14+(16\times 3)=63gmo{l}^{-1}$

$\text{Moles of}HN{O}_3=\frac{\text{Mass of}HN{O}_3}{\text{Molecular Mass of}HN{O}_3}\text{Moles of}HN{O}_3=\frac{31.5}{63}=\frac{1}{2}mol$
Strength of a solution is the ratio of mass of solute to the volume of solution in litres
$\text{Strength}=\frac{31.5\times 1000}{500}g{L}^{-1}=63g{L}^{-1}$
$\text{Molarity}=\frac{\text{Moles of solute}}{\text{Volume of solution (L)}}=\frac{1\times 1000}{2\times 500}\text{Molarity=1 M}$