MOLARITYSolutions

MOLARITY (M)

Is the number of moles of solute dissolved per Liter of solution.

Also know as molar concentration.

Unit M is read as molar

To calculate a solution’s molarity, you must know the volume of the solution and the amount of dissolved solute Molarity (M) = moles of solute liters of solution

EXAMPLE

A 100.5 mL intravenous (IV) solution contains 5.10 g of glucose (C6H12O6). What is the molarity of this solution? The molar mass of glucose is 180.16 g/mol.

Given: mass of solute= 5.10 g of glucose Molar mass of glucose= 180.16 g/mol Volume of solution = 100.5 mL

Unknown: Concentration = ?M

STEPS TO SOLVE THE EXAMPLE 1.) Use the molar mass to calculate moles of glucose

5.10 g C6H12O6 1 mole C6H12O6

180.16 g C6H12O6

2.) Convert mL to Liters

100.5 mL of solution 1 L 1,000 mL

3.) Plug in values into the formula for molarit

Molartiy = moles of solute Molarity = Liters of solution

= 0.0283 C6H12O6

= 0.1005 L of solution

= 0.282 M

0.0283 mol C6H12O6

0.1005 L of solution