1. Section 17.3 Homogeneous Aqueous Solutions

2. Solution - a homogenous mixture, that is mixed molecule by molecule.
Solvents and Solutes
Solution - a homogenous mixture, that is mixed molecule by molecule.
Solvent - the dissolving medium
Solute -the dissolved particles

3. Aqueous solution- a solution with water as the solvent.
Solvents and Solutes
Aqueous solution- a solution with water as the solvent.
Particle size less than 1 nm; cannot be separated by filtration

4. Aqueous Solutions
Water dissolves ionic compounds and polar covalent molecules best.
The rule is: “like dissolves like”
Polar dissolves polar.
Nonpolar dissolves nonpolar.

5. The Solution Process Called “solvation”
Water breaks the + and - charged pieces apart and surrounds them.
In some ionic compounds, the attraction between ions is greater than the attraction exerted by water (don’t dissolve)

6. How Ionic solids dissolve in water
These ions have been pulled away from the main crystal structure by water’s polarity. H O H O H O H O H O H O H O H O H O
These ions have been surrounded by water, and are now dissolved!

7. Electrolytes and Nonelectrolytes
Electrolytes- compounds that conduct an electric current in aqueous solution, or in the molten state
All ionic compounds are electrolytes; dissociate into ions (they are also called “salts”)

8. Electrolytes and Nonelectrolytes
Do not conduct? = Nonelectrolytes.
Most are molecular materials, because they do not have ions

9. Electrolytes and Nonelectrolytes
There are strong electrolytes (100% ions), and weak electrolytes (small fraction become ions)
Depends on: degree of ionization

10. Water of Hydration (or Water of Crystallization)
Water molecules are chemically bonded to solid salt molecules (not in solution)
These compounds have fixed amounts of water.

11. Water of Hydration (or Water of Crystallization)
The water can be driven off by heating:
CuSO4•5H2O CuSO4 + 5H2O
Called copper(II)sulfate pentahydrate.
- heat
+ heat

12. Since heat can drive off water, the forces holding it are weak
Hydrates
Since heat can drive off water, the forces holding it are weak
Some hydrates remove water from the air to form hydrates- these are called hygroscopic