# How many grams of KI are in 25.0 mL of a 3.0% (m/v) KI solution?

##### 1 Answer

Nov 17, 2015

#### Explanation:

Notice that you were given the solution's mass by volume percent concentration, which is defined as mass of solute divided by volume of solution, and multiplied by

In your case, a **for every**

You know that the volume of the sample is *four times smaller* than this value, so you can say right from the start that it will contain *four times less* potassium iodide.

#25.0color(red)(cancel(color(black)("mL solution"))) * "3.0 g KI"/(100color(red)(cancel(color(black)("mL solution")))) = color(green)("0.75 g KI")#

The answer is rounded to two sig figs, the number of sig figs you have for the given concentration.