Molarity, Molarity, and Percent Concentration

Example: What is the molarity of a solution prepared by dissolving 15.0 g of sodium hydroxide in enough water to make a total of 225 mL of solution?
Method 1:

• Calculate the number of moles of solute present.

  mol NaOH	=	30.0g NaOH	x	1 mol NaOH
  				80.0 g NaOH
  mol NaOH	=	0.750 mol NaOH

  
  
• Calculate the number of liters of solution present.

  L soln	=	500 mL	x	1 L	=	0.500 L soln
  				2000 mL

• Divide the number of moles of solute by the number of liters of solution.

  M	=	0.750 mol NaOH	=	1.67 M NaOH
  		0.500 L soln