Question

Concentration terms like mass percentage, ppm, mole fraction and molality do not depend on temperature. However, molarity is a function of temperature because:

• A. volume depends on temperature and molarity involves volume
• B. molarity involves non-volatile solute while all other terms involve volatile solute
• C. number of moles of solute change with change in temperature
• D. molarity is used for polar solvents only

Answer 1

The correct option is A volume depends on temperature and molarity involves volume

Molarity = $\frac{\text{no. of moles}}{\text{Volume of solution (L)}}$

When temperature increases the volume of the solution decreases assuming the solution is in constant pressure conditions.

$T\alpha \frac{1}{V}$

Therefore when temperature increases volume decreases and molarity increases.

Mass percentage,ppm,mole fraction and molality are solely dependant on mass which is independent of temperature.