1. Solutions & Molarity What is a solution?
Solution – homogeneous mixture
Solvent – substance present in largest amount
Solutes – other substances in the solution
Aqueous solution – solution with water as the solvent

3. Solubility Solubility of Ionic Substances
Ionic substances breakup into individual cations and anions.

4. Solubility How Substances Dissolve
A “hole” must be made in the water structure for each solute particle.
The lost water-water interactions must be replaced by water-solute interactions.
“like dissolves like”

5. Solution Composition: An Introduction
The solubility of a solute is limited.
Saturated solution – contains as much solute as will dissolve at that temperature
Unsaturated solution – has not reached the limit of solute that will dissolve

6. Solution Composition: An Introduction
Supersaturated solution – occurs when a solution is saturated at an elevated temperature and then allowed to cool but all of the solid remains dissolved
Contains more dissolved solid than a saturated solution at that temperature
Unstable – adding a crystal causes precipitation

7. Solution Composition: An Introduction
Solutions are mixtures.
Amounts of substances can vary in different solutions.
Specify the amounts of solvent and solutes
Qualitative measures of concentration
concentrated – relatively large amount of solute
dilute – relatively small amount of solute

8. Solution Composition: An Introduction
Which solution is more concentrated?

9. Solution Composition: An Introduction
Which solution is more concentrated?

10. Solution Composition: Molarity
Concentration of a solution is the amount of solute in a given volume of solution.

11. Solution Composition: Molarity
Consider both the amount of solute and the volume to find concentration.

12. Solution Composition: Molarity
Standard solution - a solution whose concentration is accurately known
To make a standard solution
Weigh out a sample of solute.
Transfer to a volumetric flask.
Add enough solvent to mark on flask.

13. Boiling Point and Freezing Point
The presence of solute “particles” causes the liquid range to become wider.
Boiling point increases
Freezing point decreases

14. Boiling Point and Freezing Point
Why does the boiling point of a solution increase?
Forming a bubble in a solution
Solute particles block some of the water molecules trying to enter the bubble.
Need higher pressure to maintain the bubble.

15. Boiling Point and Freezing Point
Colligative property – a solution property that depends on the number of solute particles present