Question

Which of the following is dependent on temperature?

• A. Molality
• B. Molarity
• C. Mole fraction
• D. Weight percentage

Answer 1

The Correct Option is B

The question asks which of the given concentration terms is dependent on temperature. Let's analyze each option to find the correct answer.

1. Molality: Molality is defined as the number of moles of solute per kilogram of solvent. The formula for molality is: \text{Molality (m)} = \frac{\text{moles of solute}}{\text{kg of solvent}} . Since both the number of moles and the mass of the solvent are unaffected by temperature changes, molality is independent of temperature.
2. Molarity: Molarity is defined as the number of moles of solute per liter of solution. The formula for molarity is: \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} . The volume of a solution can change with temperature due to thermal expansion or contraction, meaning that molarity is dependent on temperature.
3. Mole Fraction: Mole fraction is the ratio of the number of moles of a component to the total number of moles of all components in the mixture. The formula for mole fraction is: \text{Mole Fraction (X)} = \frac{\text{moles of component}}{\text{total moles}} . As it involves only moles, which are not affected by temperature, mole fraction is independent of temperature.
4. Weight Percentage: Weight percentage is the mass of solute divided by the total mass of the solution, multiplied by 100. Since mass does not change with temperature, weight percentage is independent of temperature.

Based on the analysis, the concentration term that is dependent on temperature is molarity. The volume change with temperature affects molarity, making it temperature-dependent.

Therefore, the correct answer is: Molarity.