1. Solutions, Problems, Solutions, Problems. Does it ever end?
Solution Chemistry
Solutions, Problems, Solutions, Problems.
Does it ever end?

2. How can you express concentration?

3. How can you express concentration?
Mass % composition
Molarity
Molality
Mole fraction
Density

4. Mass % problems: Find mass % Find amount of solute
Find total mass of solution

5. Mass % problems: Find mass % Mass % = mass of solute x 100 %
total mass of solution
Don’t forget to add the masses of the solute and solvent for the total mass

6. Mass % problems: Find amount of solute Mass % = mass of solute x 100 %
total mass of solution
Multiply by total mass and divide by 100% to solve for mass of solute

7. Mass % problems: Find total mass of solution
Mass % = mass of solute x 100 %
total mass of solution
Multiply both sides by the mass of solution first to get it out of the denominator.

8. Molarity problems: Find molarity Find amount of solute
Find volume of solution

9. Molarity problems: Find molarity M= moles solute
Volume of solution (L)

10. Molarity problems: Find amount of solute M= moles solute
Volume of solution (L)
Molarity x volume= moles!

11. Molarity problems: Find volume of solution M= moles solute
Volume of solution (L)
Multiply both sides by the volume of solution first to get it out of the denominator.
OR!

12. Molarity problems: Find volume of solution
Use the molarity as a conversion factor!
moles solute x 1 L = Volume of solution! M

13. Dilution problems M x V = Moles
Moles of solute in new solution = moles in the stock solution. Molarity goes down, volume goes up

14. Dilution problems Example:
What is the concentration of a solution made by diluting 25 ml of a .50 M HCl solution to a new volume of 150 ml?

15. Dilution problems Example:
What is the concentration of a solution made by diluting 25 ml of a .50 M HCl solution to a new volume of 150 ml?
M x V = moles.
.50 M x .025 L= moles HCl
M = mol/vol= mol / .150 L = .083 M

16. Dilution Problems
What is the concentration of a solution made by diluting 125 ml of a 2.5 M NH3 solution to a new volume of 350 ml?
What is the concentration of a solution made by diluting 2.5 ml of a 6.0 M NaCl solution to a new volume of 80. ml?
What is the concentration of a solution made by diluting 30. ml of a 1.0 M Fe(NO3)3 solution with 20. ml of water? (The final volume should be = 50. ml)

17. Dilution problems Example:
What volume of a 2.0 M NaOH stock solution is required to mix 1.50 L of a .150 M NaOH solution?

18. Dilution problems Example:
What volume of a 2.0 M NaOH stock solution is required to mix 1.50 L of a .150 M NaOH solution?
M x V = moles.
.150 M x 1.50 L = .225 moles NaOH
.225 moles NaOH x 1 L/ 2.0 moles= .113 L

19. Dilution problems
What volume of a 6.0 M NaOH stock solution is required to mix 1.50 L of a .150 M NaOH solution?
What volume of a 2.0 M MgCl2 stock solution is required to mix .750 L of a .10 M MgCl2 solution?
What volume of a 1.0 M HCl stock solution is required to mix 100. ml of a .10 M HCl solution?