Chemistry - Concentration Terms Question with Solution | TestHub

Question Explanation:

Identify which concentration terms are unaffected by temperature changes.

Concept:

The effect of temperature on the components of concentration formulas.

Solution:

Concentration terms are classified based on their dependence on temperature.

Molarity (M) is defined as the number of moles of solute per liter of volume of the solution $\left(\mathrm{M}=\frac{{\mathrm{n}}_{\text{solute }}}{{\mathrm{V}}_{\text{solution }}}\right)$. Since the volume of a solution changes with temperature (generally increases with a temperature increase), molarity is temperature-dependent.

In contrast, molality (m) is defined as the number of moles of solute per kilogram of mass of the solvent $\left(\mathrm{m}=\frac{{\mathrm{n}}_{\text{solute }}}{{\mathrm{W}}_{\text{solvent }}(\mathrm{kg})}\right)$, and

mole fraction ( x ) is the ratio of moles of a component to the total moles ( ${\mathrm{x}}_{\mathrm{A}}=\frac{{\mathrm{n}}_{\text{solute }}}{{\mathrm{n}}_{\text{solution }}}$ ). As mass and the number of moles do not change with temperature, both molality and mole fraction are temperature-independent.

Final Answer:

The correct answer is option C.