Question

Which of the following statement is true?

• A. Molarity of solution is independent of temperature
• B. Molality of solution is independent of temperature,
• C. Mole fraction of solute is dependent on temperature
• D. The unit of molality is $mol \,dm ^{-3}$

Answer 1

Answer: (B)

(1) $M=\frac{w}{M_{w} \times V(L)} $
$M \propto \frac{1}{\text { Volume }}$
$M$ - Depends on volume so it also depends on temperature. $PV = nRT$
(2) Molality $=\frac{ w }{ M _{ w } \times W _{\text {solvent }}( kg )}$
Molality does not depend on volume so it does not depend on temperature.
(3) Mole fraction also does not depend on volume, so not on temperature
(4) $m =\frac{ w }{ M _{ w } \times w _{\text {solvent }( kg )}}$
$=\frac{ mol }{ kg }\left( not \rightarrow \frac{ mol }{ dm ^{3}}\right)$