You re asked to prepare 120 milliliters of a 65% solution and you have in stock 75% solution. How many milliliters of the 75% solution will you use?

Answer 1

Use the dilution equation.

C_iV_i = C_fV_f

C_i = 75%

V_i = ?

C_f = 65%

V_f = 120 mL

Rearrange the above equation and solve for V_i

V_i = C_fV_f / C_i = (65% x 120 mL) / 75% = 104 mL