Question

A sample of nitric acid is $69\%$ by mass and it has a concentration of $15.44$ moles per litre. Its density is

• A. $1.86g/cc$
• B. $1.41g/cc$
• C. $2.60g/cc$
• D. $1.02g/cc$

Answer 1

Answer: (B)

Volume of $100g$ sample $=\frac{\text{ Mass }}{\text{ Density }(d)}$
$=100/d$
Molarity $$\begin{gathered} =\frac{\text{ Mass of solute }}{\text{ Molar mass of solute }} \\ \times \frac{1000}{\text{ Volume of solution }(\text{ in mL) }} \end{gathered}$$
Molarity $=\frac{69}{63}\times \frac{1}{100/d}\times 1000$
$15.44=\frac{69}{63}\times \frac{1}{100/d}\times 1000$
$d=\frac{63\times 15.44}{69\times 10}=1.409g/cc\approx 1.41g/cc$