Question

How many milliliters of a 6.50 M stock solution would be required to produce 500 mL of a 0.25 M dilute solution? Ms:Md: Vs:Vd: Answer:

Answer 1

You can see that Ms and Vs correspond to the stock solution, whereas Md and Vd corresponds to the dilute solution. The word 'M' means concentration and 'V' means volume. We want to know what is the volume of the stock solution (Vs). So, we have to use the following formula:

`C_1V_1=C_2V_2.`

Where C is concentration and V volume. We can write this formula in our terms, like this:

`M_sV_s=M_dV_d.`

Let's solve for 'Vs':

`V_s=(M_dV_d)/(M_s)\text{.}`

The given data is:

`\begin{gathered} M_s=6.50\text{ M,} \\ M_d=0.25M,_{} \\ V_d=500\text{ mL.} \end{gathered}`

So, replacing these values in the last formula, we're going to obtain:

`V_s=\frac{0.25\text{ M }\cdot\text{ 500 mL}}{0.25\text{ M}}=19.2307\text{ mL}\approx19.2\text{ mL.}`

The answer is that we have 19.2 milliliters (mL) in the stock solution.