Question

Question #651e9

Answer 1

`V_(C_3H_8O) = "330 mL"`

Explanation:

A solution's percent concentration by volume is defined as the volume of the solute, which in your case is isopropyl alcohol, `"C"_3"H"_8"O"`, divided by the total volume of the solution, and multiplied by `100`.

`color(blue)("% v/v" = "volume of solute"/"volume of solution" xx 100)`

In your case, rubbing alcohol is said to contain `"70. %v/v"` isopropyl alcohol. What that means is that every `"100 mL"` of rubbing alcohol will contain `"70. mL"` of isopropyl alcohol.

You're interested in finding out how much isopropyl alcohol you get in `"473 mL"` of rubbin alcohol, so you can say that

`473 color(red)(cancel(color(black)("mL rubbing alcohol"))) * ("70. mL C"_3"H"_8"O")/(100color(red)(cancel(color(black)("mL rubbing alcohol")))) = "331.1 mL C"_3"H"_8"O"`

You need to round this off to two sig figs, the number of sig figs you have for the percent concentration by volume

`V_(C_3H_8O) = color(green)("330 mL")`