Question

You have a stock solution that is 178 mg/mL and you need 10 mL of a working solution that is 45 mg/mL. What volume of stock solution will you need to dilute to have 10 mL of working solution at the above concentration? State your answer to two decimals and do not include units in your answer.

Answer 1

Answer : The volume of stock solution needed will be, 2.53 mL

Explanation : Given,

Stock solution = 178 mg/mL

Working solution = 45 mg/mL

Volume of working solution = 10 mL

Formula used :

`V_1M_1=V_2M_2`

where,

`M_1` = concentration of Stock solution

`M_2` = concentration of working solution

`V_1` = volume of stock solution

`V_2` = volume of working solution

Now put all the given values in the above formula, we get:

`V_1* (178mg/mL)=(10mL)* (45mg/mL)`

`V_1=2.53mL`

Thus, the volume of stock solution needed will be, 2.53 mL