Chapter 19, Problem 5TS

If water is added to $\text{1}$ mole of sodium chloride in a flask until the volume of the solution is $\text{1 L}$, what is the molarity of the solution? What is the molarity when water is added to $\text{2}$ moles of sodium chloride to make $\text{0}\text{.5 L}$ of solution?

To determine

The molarity of sodium chloride solution.

Answer to Problem 5TS

Molarity of $\text{1 L}$ sodium chloride solution when it contains $\text{1}$ mole sodium chloride is $\text{1 M}$ and Molarity of $\text{0}\text{.5 L}$ sodium chloride solution when it contains $\text{2}$ moles sodium chloride is $\text{4 M}$.

Explanation of Solution

Molarity is way of expressing concentration of the solution it is the number of moles of the substance per litre of solution. Moles of sodium are $\text{1}$ and volume of solution is 1 L. Calculate molarity using the formula as shown below:

$\begin{array}{c}\text{Molarity}=\frac{\text{moles of solute}}{\text{volume of solution (L)}}\\ =\frac{\text{1 mole NaCl}}{\text{1 L solution}}\\ =1\text{ M}\end{array}$

Molarity of 0.5 L sodium chloride solution when it contains $\text{2}$ moles sodium chloride is,

$\text{Molarity}=\frac{\text{2 mole NaCl}}{\text{0}\text{.5 L solution}}=4\text{ M}$

Conclusion:

Therefore, molarity of $\text{1 L}$ sodium chloride solution when it contains $\text{1}$ mole sodium chloride is $\text{1 M}$ and Molarity of $\text{0}\text{.5 L}$ sodium chloride solution when it contains $\text{2}$ moles sodium chloride is $\text{4 M}$.