Question

How many mL of 0.626 M NaOH solution are needed to obtain 0.332 mol of NAOH?

Answer 1

Any time we are working with solutions and its molar concentration we will use the equation:

`C=\frac{n_{\text{solute}}}{V_{\text{solution}}}`

Where C is the concentration, n is the number of moles of the solute and V is the volume of solution.

We can identify such situations when we are working with molarity, molar concentration, solutions with concentration in "M" or "mol/L" units and other cases.

In this case, we can see that we are working with these three quantities:

- We want the volume in mL os a solution, V.

- We have a molar concentration, C, 0.626 M NaOH.

- We have a number of moles of solute we want to get, n, 0.332 mol of NaOH.

So, we have:

`\begin{gathered} V_{\text{solution}}=\; \text{?} \\ C=0.626M=0.626mol/L \\ n_{\text{solute}}=0.332mol \end{gathered}`

So:

`\begin{gathered} C=\frac{n_{\text{solute}}}{V_{\text{solution}}} \\ V_{\text{solution}}=\frac{n_{\text{solute}}}{C}=(0.332mol)/(0.626mol/L)=0.530351\ldots L=530.351\ldots mL\approx530mL \end{gathered}`

So, the volume we need is approximately 530 mL.