Question

You need 455 mL of a 5% alcohol solution. On hand, you have a 65% alcohol mixture. How much of the 65% alcohol mixture and pure water will you need to obtain the desired solution?

You need :
___ ml of pure water
And
___ ml of the 65% solution

Answer 1

You need: 420 mL pure water and 35 mL of the 65% solution

Explanation:

let 65% alcohol mixture = x mL

y = water

x + y = 455

0.65x / 455 = 0.05

0.65x = 22.75

x = 35

recall, 35 + y = 455

y = 420

You need: 420 mL pure water and 35 mL of the 65% solution