Question

The value of which of the following unit of concentration will not change with the change in temperature?

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

Answer 1

The correct option is B

Molality

Explanation for correct option

(B)Molality

• Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent.
• It does not depend on temperature because mass does not depend on temperature.

Explanation for incorrect option

Molarity

• Molarity is defined as the number of moles of solute dissolved in one liter (or one cubic decimetre) of the solution.
• The symbol for molarity is M.
• It is a function of temperature. This is because volume depends on temperature.

Normality

• It is the number of gram or mole equivalents of solute present in one liter of a solution.
• It also depends on temperature.

Formality

• A solution's formality is determined by how many grams of solute there are per litre of the solution.
• It also depends on temperature.

Hence, options (A), (C), and (D) are incorrect.

Hence, option (B) is correct. Molality will not change with the change in temperature.