1. Solution Concentration (Molarity)

2. Parts of a Solution
solute – the part of a solution that is being dissolved (usually the lesser amount)
solvent – the part of a solution that dissolves the solute (usually the greater amount)
solution = solute + solvent
Solute
Solvent
Solution Si Al
metal alloy
salt
water
salt water
CO2
carbonated water O N
air

3. Concentration
a measure of the amount of solute that is dissolved in a given quantity of solvent
Molarity (M) which is moles/volume
volume must be in liters
often use square brackets to mean concentration
[HCl] = 1.0 M

4. Molarity = Molarity moles solute liters of solution
The number of moles of solute dissolved in liters of solution
Molarity =
moles solute
liters of solution

5. 1. 0 L of water was used to make 1. 0 L of solution
1.0 L of water was used to make 1.0 L of solution. Notice the water left over. 1.0L of water would be too much.

6. Making a known molar solution
top off to 1 liter

7. What is the concentration of 2 moles of HCl in 4 L?
2 mol / 4 L = 0.5 M

8. Step 1: Convert 5 g of NiCl2• 6H2O to moles
PROBLEM: Dissolve 5.00 g of NiCl2•6 H2O in enough water to make 250 mL of solution. Calculate the Molarity.
Step 1: Convert 5 g of NiCl2• 6H2O to moles
1.0 L = 1000 mL
.25 L = 250 mL
Step 2: Calculate Molarity

9. M = moles/V same as moles = M•V
USING MOLARITY
What mass of oxalic acid, H2C2O4, is required to make 250 mL of a M solution?
M = moles/V same as moles = M•V
Step 1: Change mL to L.
250 mL/1000 = L
Step 2: Calculate.
moles = ( M) (0.250 L) = moles H2C2O4
Step 3: Convert moles to grams.
( mol H2C2O4) (90.00 g) = g
1 mol H2C2O4

10. Learning Check
How many grams of NaOH are required to prepare 400 mL of 3.0 M NaOH solution?
1) 12 g
2) 48 g
3) 300 g