Question #651e9

1 Answer
Dec 11, 2015

Answer:

#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")#