Question

How much 3M NaOH (MW=40) can be made from 10.0mL of a 10M solution?

Answer 1

Explanation:

The given data is as follows.

              $M_{1}$ = 3 M,           $V_{1}$ = ?

              $M_{2}$ = 10 M,         $V_{2}$ = 10.0 ml

Therefore, calculate the volume of given solution as follows.

              $M_{1} \times V_{1}$ = $M_{2} \times V_{2}$

Now, putting the given values into the above formula as follows.

            $M_{1} \times V_{1}$ = $M_{2} \times V_{2}$

            $3 M \times V_{1}$ = $10 M \times 10.0 ml$    

                   $V_{1}$ = 33.3 ml

or,                             = 0.033 L        (as 1 ml = 0.001 L)

Since, molarity of NaOH is given as 3 M and its volume is calculated as 33.3 ml.

           Molarity = $\frac{\text{mass of solute}}{\text{molar mass of solute}} \times \frac{1}{\text{volume in L}}$

               3 M = $\frac{mass}{40 g/mol \times 0.033 L}$

              mass = 3.96 g

Therefore, we can conclude that mass of NaOH is 3.96 g.