1. Molarity

2. Concentration Based on Mass
Concentration - amount of solute dissolved in a given amount of solution
Concentration of a solution has an effect on
Physical properties
Melting and boiling points
Chemical properties
Solution reactivity

3. Moles and Equivalents
Chemical equations represent the relative number of moles of reactants producing products
Many chemical reactions occur in solution where it is most useful to represent concentrations on a molar basis

4. Molarity The most common mole-based concentration unit is molarity
Symbolized M
Defined as the number of moles of solute per liter of solution

5. Molarity
2M HCl
What does this mean?

6. Molarity Calculations
6.02  1023
(particles/mol)
molar mass
(g/mol)
MASS IN
GRAMS
MOLES
NUMBER OF
PARTICLES
LITERS
SOLUTION
Molarity
(mol/L)

7. Calculating Molarity from Moles
Calculate the molarity of 2.0 L of solution containing 5.0 mol NaOH
Use the equation
Substitute into the equation:
MNaOH = 5.0 mol solute
2.0 L solution
= 2.5 M

8. Molarity Calculations
How many grams of NaCl are required to make 0.500L of 0.25M NaCl?
0.500 L
0.25 mol
1 L
58.44 g
1 mol
= 7.3 g NaCl

9. Molarity Calculations
Find the molarity of a 250 mL solution containing 10.0 g of NaF.
10.0 g
1 mol
41.99 g
= mol NaF
0.238 mol
0.25 L
M =
= 0.95M NaF

10. Molar Volume of a Gas
Molar volume - the volume occupied by 1 mol of any gas
STP – Standard Temperature and Pressure
T = 273 K (or 0oC)
P = 1 atm
At STP the molar volume of any gas is 22.4 L
Vgas = molesgas x (22.4L/1 mol)

11. Molar Mass and Density
A gas’s density will determine if it will sink or float in the air
Molar mass = density x molar volume
At STP