Question

You have a 100 ml stock solution of 100 mg/ml ampicillin in deionized water. You want to make 30 ml of 25 mg/ml ampicillin in deionized water. How many milliliters (ml) of 17 ampicillin stock and how many of deion ized water are needed to make this stock solution? atealk

Answer 1

Explanation:

Volume of the stock solution is $V_{1}$ = ?

Initial concentration of ampicillin is $M_{1}$ = 100 mg/ml

Final volume ($V_{2}$) = 30 ml

Final concentration of  ampicillin ($M_{2}$) = 25 mg/ml

Therefore, calculate the volume of given stock as follows.

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

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

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

            $100 mg/ml \times V_{1}$ = $25 g/ml \times 30 ml$    

                   $V_{1}$ = 7.5 ml

Now, we will calculate the volume of water added into it as follows.

            Volume of water added = $V_{2} - V_{1}$

                                                  = 30 ml - 7.5 ml

                                                  = 22.5 ml

Thus, we can conclude that required solution is 22.5 ml of deionized water.