A teacher needs to make 120.0 mL of a 4.00 M HCl solution using a stock solution with a concentration of 12.0 M. Determine the volume of 12.0 M HCl needed to make the dilution.
c1 = 12.0 M
V1 = unknown
c2 = 4.00 M
V2 = 120.0 mL
The equation for dilution calculations can be used.
c1, V1 - the molarity and volume of the concentrated solution
c2, V2 - the molarity and volume of the diluted solution
(12.0 M) × V1 = (4.00 M) × (120.0 mL)
V1 = (4.00 M × 120.0 mL) / (12.0 M) = 40 mL
V1 = 40 mL
Answer: 40 mL of 12.0 M HCl needed to make the dilution.