You need 525 mL of a 40% alcohol solution. On hand, you have a 25% alcohol mixture. How much of the 25% alcohol mixture and pure alcohol will you need to obtain the desired solution?

Question

you will need

____mL of 25% solution and

____mL of of pure alcohol

Answer 1

Hello Natalie,

Let X = the amount of alcohol mixture and pure alcohol needed

(0.40)(525mL) = the desired alcohol solution

(0.25)(525mL - X) = alcohol mixture on hand

(0.40)(525mL) = (0.25)(525mL - X) + X

210mL = 131.25mL - 0.25X + X

210mL = 131.25mL + 0.75X

78.75mL = 0.75X

105mL = X

you will need

105mL of 25% solution and

105mL of of pure alcohol