Question

Casey is completing an experiment that requires a 300 mL solution with a 20% concentration of potassium chloride (KCl). But Casey's lab only stores potassium chloride at concentrations of 10% and 50%. How much 10% KCl solution will Casey have to mix with 50% KCl solution to make 300 mL of 20% KCl solution?

Answer 1

            We have to mix 10% KCl solution with 50%  KCl solution to get 20% concentration.            We have x mL of 10% solution and y mL of 50% solution.            20% - 10% = 10% and 50% - 20% = 30%            x : y = 30 : 10            x : y =  3 : 1            x = 3 y            x + y = 300            3 y + y = 300            4 y = 300            y = 300 : 4            y = 75            x = 300 - 75 = 225Answer: Casey will have to mix 225 mL 10% KCl solution with 75 mL 50% solution.