Question

A student needs to prepare 50.0 mL of a 1.20 M aqueous H2O2 solution. Calculate the volume of 4.9 M H2O2 stock solution that should be used to prepare the solution.

Answer 1

Answer : The volume of 4.9 M $H_2O_2$ stock solution used to prepare the solution is, 12.24 ml

Solution : Given,

Molarity of aqueous $H_2O_2$ solution = 1.20 M = 1.20 mole/L

Volume of aqueous $H_2O_2$ solution = 50.0 ml = 0.05 L

(1 L = 1000 ml)

Molarity of $H_2O_2$ stock solution = 4.9 M = 4.9 mole/L

Formula used :

$M_1V_1=M_2V_2$

where,

$M_1$ = Molarity of aqueous $H_2O_2$ solution

$M_2$ = Molarity of $H_2O_2$ stock solution

$V_1$ = Volume of aqueous $H_2O_2$ solution

$V_2$ = Volume of $H_2O_2$ stock solution

Now put all the given values in this formula, we get the volume of $H_2O_2$ stock solution.

$(1.20mole/L)\times (0.05L)=(4.9mole/L)\times V_2$

By rearranging the term, we get

$V_2=0.01224L=12.24ml$

Therefore, the volume of 4.9 M $H_2O_2$ stock solution used to prepare the solution is, 12.24 ml