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 :
[tex]V_1M_1=V_2M_2[/tex]
where,
[tex]M_1[/tex] = concentration of Stock solution
[tex]M_2[/tex] = concentration of working solution
[tex]V_1[/tex] = volume of stock solution
[tex]V_2[/tex] = volume of working solution
Now put all the given values in the above formula, we get:
[tex]V_1\times (178mg/mL)=(10mL)\times (45mg/mL)[/tex]
[tex]V_1=2.53mL[/tex]
Thus, the volume of stock solution needed will be, 2.53 mL