# What is the molarity of a solution made using 2.19 g of KI dissolved in enough water to make 266 mL of solution?

Mar 28, 2015

The molarity of the solution will be $\text{0.0496 M}$.

Molarity is defined as moles of solute, in your case potassium iodide, divided by liters of solution.

Since the volume of the solution is given to you, all you need to do is figure out how many moles of potassium iodide you have. Use the compound's molar mass to go from grams to moles

$\text{2.19"cancel("g") "KI" * "1 mole KI"/(166.0cancel("g")) = "0.0132 moles KI}$

As a result, the solution's molarity will be

$C = \frac{n}{V} = \text{0.0132 moles"/(266 * 10^(-3)"L") = "0.0496 M}$

SIDE NOTE Don't forget to use liters, not mililiters, when calculating molarity.