Question

Which of the following concentration units is independent of temperature ?

• A. Normality
• B. Molarity
• C. Formality
• D. Molality

Answer 1

Answer: (D)

Volume is temperature dependent term. The expression which does not have volume term is independent of temperature.

(i) Normality $=\frac{\text{ gram equivalents of solute }}{\text{ volume of solution in litre }}$

(ii) N.olarity $=\frac{\text{ moles of solute }}{\text{ volume of solution in litre }}$

(iii) Formality $=\frac{\text{ formula weight }}{\text{ volume of solution in litre }}$

(iv) Molality $=\frac{\text{ moles of solute }}{\text{ mass of solvent in }kg}$

$\because$ molality does not involve volume term.

$\therefore$ it is independent of temperature.