Question

What happens to the molarity of a salt solution if the number of moles of salt in the solution is multiplied by three and the number of liters of the solution is also multiplied by three? The molarity of the solution remains unchanged. The molarity of the solution becomes three times as much. The molarity of the solution becomes six times as much. The molarity of the solution decreases.

Answer 1

Answer:

The molarity of the solution remains unchanged.

Explanation:

Consider the formula for the molarity $M$ of a solution:

$\displaystyle M = \frac{n}{V}$,

where

• $n$ is the number of moles of solute in this solution, and
• $V$ is the volume of the solution.

For this salt solution,

• $n_{1} = 3\;n_{0}$, and
• $V_{1} = 3\;V_{0}$.

Initial molarity:

$\displaystyle M_{0} = \frac{n_{0}}{V_{0}}$.

Final molarity:

$\displaystyle M_{1} = \frac{n_{1}}{V_{1}} = \frac{3\;n_{0}}{3\;V_{0}} = \frac{n_{0}}{V_{0}} = M_{0}$.

In other words, the molarity of the solution remains unchanged.