Unit V: The Mole

1. Percent Composition What’s a Mole? Empirical & Molecular Formulae Molar Mass Unit V: The Mole Dilutions Molar Volume Molar Concentration Density & Molar Volume

2. Molarity Review • The chemical stores room is running low on 0.10M barium chloride solution. You look around and find we only have 6.42g of barium chloride salt left. What volume of 0.10M barium chloride solution can we make with this amount of salt? • Neutral water has a hydroxide ion concentration of 1 x 10-7M. How many hydroxide ions are there in a 3.004nL sample of water?

3. The Heart of the Mole Conversion Sheet Volume of a Solution (L) Number of Particles Mole (mol) volume of a solid or liquid (L) Density of a gas at STP: Volume of a gas at STP (L) Mass (g)

4. Dilutions and Distillationss • The concentration of an aqueous solution may be altered by either adding water (dilution) or allowing water to escape the solution (distillation). • When either of these procedures are performed, the volume of the solution will change and the concentrationof the solution will change, but the number of moles of solutewill remain the same. Distillation Dilution n = 2 moles V = 2L C = 1M n = V = 4L C = n = V = 1L C =

5. Dilutions and Distillationss • The concentration of an aqueous solution may be altered by either adding water (dilution) or allowing water to escape the solution (distillation). • When either of these procedures are performed, the volume of the solution will change and the concentrationof the solution will change, but the number of moles of solutewill remain the same. Distitllation Dilution n = 2 moles V = 2L C = 1M n = 2 moles V = 4L C = 0.5M n = 2 moles V = 1L C = 2M

6. Solving Dilution and Distillation qs • There are two methods for these questions Method 1: 0.40L of water was added to 2.20L of 0.751M CoCl2 solution. What is the concentration of the new solution? Step 1: Find the number of moles of solute in the initial solution, since that value will not change in a dilution or distillation Step 2: Find the volumeof the final solution Step 3: Find the molarity of the final solution by using these two values.

7. Solving Dilution and Distillation qs • There are two methods for these questions Method 2: 0.40L of water was added to 2.20L of 0.751M CoCl2 solution. What is the concentration of the new solution? Step 1: Since the number of moles in the initial and final solution is the same, we can make an equation: And since molarity x volume = the number of moles, Step 2: List all the values we know, and assign them variables: Step 3: Plug these values into your equation and solve for your unknown

8. Practice Dilution Questions • If 200.0mL of 0.500M HgCl2 is added to 300.0mL of water, what is the resulting [HgCl2] in the mixture?

9. Mixing Solutions Together • If 300.0mL of 0.250M NaCl is added to 500.0mL of 0.100M NaCl, what is the resulting [NaCl] in the mixture?

10. Practice with Mixture Problems • What is the [CaCl2] produced by mixing 145mL of 0.550M CaCl2 with 55mL of 0.135M CaCl2?