# Question #ba500

##### 1 Answer

#### Explanation:

The problem provides you with the **volume** of solute, which in your case is ethanol, **volume** of solvent, which in your case is water, so right from the start you know that you're looking for the solution's **volume by volume percent concentration**,

The solution's volume by volume percent concentration tells you how many cubic centimeters of solute you get **for every** **of solution**. The first thing to do here will be to figure out the **total volume** of the solution.

#V_"total" = V_"solute" + V_"solvent"#

In your case, you have

#V_"total" = "40 cm"^3 + "160 cm"^3 = "200 cm"^3#

Now, you know that you have

#100 color(red)(cancel(color(black)("cm"^3color(white)(a)"solution"))) * ("40 cm"^3color(white)(a)"CH"_3"CH"_2"OH")/(200color(red)(cancel(color(black)("cm"^3color(white)(a)"solution")))) = "20 cm"^3color(white)(a)"CH"_3"CH"_2"OH"#

So, if

#"% v/v" = color(green)(|bar(ul(color(white)(a/a)color(black)("20% CH"_3"CH"_2"OH")color(white)(a/a)|)))#