1. Aqueous Solutions
Section 17.3

2. After reading Section 17.3, you should know:
The meaning of “likes dissolve likes” and how to determine which compounds will dissolve into each other
The difference between strong, weak and non- electrolytes
The difference between hygroscopic and deliquescent substances

3. Solvent vs Solute
Aqueous Solutions – water samples containing dissolved substances
Solvent – the substance doing the dissolving
Solute – the substance being dissolved
Example of an aqueous solution = salt water
Solvent = water
Solute = salt

4. Review: Ionic and Covalent
Ionic comounds = metal + nonmetal
Held together by ionic charges
Polar Covalent molecules = 2 or more nonmetals
Have a slight charge due to electronegativity differences
Nonpolar Covalent molecules = 2 or more nonmetals
Do not have a charge because the shape of the molecule cancels the electronegativity differences out

5. “Likes Dissolve Likes”
Ionic compounds and polar compounds will dissolve in other ionic and polar compounds
Ionic compounds have a full charge and polar compounds have a slight charge, so the charges are attracted to each other.
Nonpolar compounds will only dissolve in other nonpolar compounds

6. Salt will dissolve in water
Salt is ionic, water is polar
Oil and water do not mix
Oil is nonpolar and water is polar

7. Solutions Solutions are homogenous mixtures
Solvation – the process that occurs when a solute dissolves
Example: salt dissolving in water
Salt is an ionic compound, water is a polar molecule
Animation of salt water and the interactions between the molecules

8. Electrolytes and Nonelectrolytes
Electrolytes – compounds that conduct an electric current in aqueous solution or the molten state
All ionic compounds are electrolytes
Nonelectrolytes - compounds that do not conduct an electric current in aqueous solution or the molten state

9. Strong electrolyte – when a substance is dissolved and almost all of the solute molecules separate into ions
Weak electrolytes – when a substance is dissolved and only a fraction of the dissolved solute separate into ions
Table 17.3 on page 485

10. Water of Hydration
Water of hydration is the water contained in a crystal
Hydrate – a compound containing water
Example: copper (II) sulfate pentahydrate
CuSO4*5H2O
Table 17.4 on page 486

11. Hygroscopic – substances that remove water from the air
Effloresce – process that occurs when a hydrate has a vapor pressure higher than that of water vapor in the air
Hygroscopic – substances that remove water from the air
Have low vapor pressure
Used as desiccants or drying agents

12. Deliquescent – compounds that remove a sufficient water from the air to dissolve completely and form solutions
When a substance has a lower vapor pressure that that of the water in the air
Example: solid NaOH pellets – react with moisture from the air and will “melt” over time

13. After reading Section 17.3, you should know:
The meaning of “likes dissolve likes” and how to determine which compounds will dissolve into each other
The difference between strong, weak and non- electrolytes
The difference between hygroscopic and deliquescent substances