Question

Calculate the density of an aqueous solution of $K I$ if its molarity and molality are $1.44\, M$ and $1.5\, mol.\, kg ^{-1}$ respectively .

• A. $2.20\, gL ^{-1}$
• B. $2.50\, gL ^{-1}$
• C. $1.20\, gL ^{-1}$
• D. $0.50\, gL ^{-1}$

Answer 1

Answer: (C)

We know,
$m=\frac{1000 \times M}{1000 \times d-M \times M_{B}}$
$\Rightarrow d=\frac{1000 \times M +m \times M \times M_{B}}{1000 \times m}$
$=\frac{1000 \times 1.44+1.5 \times 1.44 \times 166}{1000 \times 1.5}$
$=1.1990=1.20\, g\,L ^{-1}$
$\because m =$ molality $=1.5\, mol\, kg ^{-1}$
$M=$ molarity $=1.44\, mol\,L ^{-1}$
$=166\, g\,mol ^{-1}$
$d=$ density of solution