Question

The four most common ways to describe solution composition are mass percent, mole fraction, molarity, and molality. Define each of these solution composition terms. Why is molarity temperature-dependent, whereas the other three solution composition terms are temperature-independent?

Short answer

The molarity is dependent on volume.

Step-by-step solution

Step 1:Concept

Molarity (M) of a solution is equal to the moles of solute per volume of the solution $\text{M}=\frac{\text{moles of solute}}{\text{liters of solution}}$. .

Molality (m) of a solution is equal to the moles of solute per kilogram of solvent $\text{m}=\frac{\text{moles of solute}}{\text{kilogram of solvent}}$.

The molarity is dependent on temperature because it depends on the volume of the solution.

Step 2:Explain the reasoning

Mass percentis percent solute by mass in the solution.

$\text{Mass percent}=.\frac{\text{grams of solute}}{\text{grams of solution}}$.

Mole fractionis a unit of the amount of a constitute, divided by the total amount of all constituents in a mixture.

${\chi }_i=\frac{{\text{n}}_{\text{i}}}{{\text{n}}_{\text{to}t}}$.

The molarity is dependent on volume, which is temperature dependent. Other three expressions depend on mass which is temperature independent.