Hey there!:
According to lew of dilution :
M*V = M'*V'
Where :
M = concentration of stock solution = 5.0% ( m / V )
V = volume of stock solution = 125 mL
M' = concentration of dilute solution = 2.5% ( m/V)
V' = volume of dilute solution = ??
Plug the values we get:
V' = m*V / M'
V' = 5.0 * 125 / 2.5
V' = 625 / 2.5
V' = 250 mL
Therefore , the volume prepared is 250 mL
Hope that helps!
