Question

An alcohol-water solution is by volume 40.0% isopropyl alcohol. There is 500.mL of the solution. How many mL of alcohol were added to water when preparing the solution?

Answer 1

`200` mL

Explanation:

With a total solution of `500` mL, you can say that is `100%` of your solution. You also know that there are `x` mL of isopropyl alcohol making up `40%` of your total soultion. With this information you can set up a proportion.

`500/100=x/40`

`5=x/40`

`200=x`

This means you added `200` mL to the water.