January 5th 2011 - Molarity

Today we learned how to find the molarity of a substance when given the component of it.
The formula for finding molarity is moles of solute / liters of solution.

For example, let's do this question.
What is the molarity of a solution containing 0.32 moles of NaCl in 3.4 L?

		molarity =	0.32 moles NaCl 3.4 L
		=	0.094 M NaCl

When given different pieces of information, just find the number of moles and the number of liters to solve for molarity again.

What is the molarity of a solution made by dissolving 2.5 g of NaCl in enough water to make 125 ml of solution?

2.5 g NaCl x

1 mole NaCl 58.5 g NaCl

= 0.0427 mole

molarity =	0.0427 mole NaCl 0.125 L
=	0.34 M NaCl