Calculate the density of an aqueous solution of KI, if its molarity and molality are \(1.44 \mathrm{M}\) and…
Calculate the density of an aqueous solution of KI, if its molarity and molality are \(1.44 \mathrm{M}\) and \(1.5 \mathrm{~mol} \mathrm{~kg}^{-1}\) respectively.
\(2.20 \mathrm{~g} \mathrm{~L}^{-1}\)
\(2.50 \mathrm{~g} \mathrm{~L}^{-1}\)
\(1.20 \mathrm{~g} \mathrm{~L}^{-1}\)
\(0.50 \mathrm{~g} \mathrm{~L}^{-1}\)
Solution
We know,
\(\begin{aligned}
m & =\frac{1000 \times M}{1000 \times d-M \times M_B} \\
\Rightarrow d & =\frac{1000 \times M+m \times M \times M_B}{1000 \times m} \\
= & \frac{1000 \times 1.44+1.5 \times 1.44 \times 166}{1000 \times 1.5} \\
& =1.1990=1.20 \mathrm{gL}^{-1} \\
m & =\text { molality }=1.5 \mathrm{~mol} \mathrm{~kg}^{-1} \\
M & =\text { molarity }=1.44 \mathrm{~mol} \mathrm{~L}^{-1} \\
M_B & =\text { molar mass of } \mathrm{KI} \\
& =166 \mathrm{~g} \mathrm{~mol}^{-1} \\
d & =\text { density of solution }
\end{aligned}\)