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Molarity versus Molality
- Molarity (M) - moles of solute per liter of solution.
- Molality (m) - moles of solute per kilogram of solvent.
These will NOT be given to you on the test. You must memorize them.
- Compounds with Group 1 elements are soluble or the ammonium ion are soluble.
- Nitrates, acetates, chlorates, and perchlorates are soluble.
- Chlorides, bromides, and iodides are generally soluble, unless they contain copper, silver, lead, or mercury.
- Sulfates are soluble, unless they contain barium, lead, silver, strontium, or calcium.
- Most silver salts are insoluble unless listed in rule #2.
- Most hydroxide salts are insoluble unless stated in rule #1 or contain calcium, strontium, or barium.
- Most sulfides are insoluble unless stated in rule #1, or contain Group 2 elements.
- Carbonates and phosphates are insoluble unless listed in rule #1.
Forgot Your Polyatomic Ions?
- Ammonium - NH4+
- Nitrate - NO3-
- Acetate - CH3COO-
- Chlorate - ClO3-
- Perchlorate - ClO4-
- Sulfate - SO42-
- Carbonate - CO32-
- Phosphate - PO43-
- Solids are more soluble when they are warm, but gases are the opposite.
- Supersaturated solutions will settle if disturbed.
Colligative properties are properties of solutions that depend on the amount of solute particles present rather than the identity of the particles.
- Vapor pressure lowering
- Freezing point depression and boiling point elevation (molality)
- Osmotic pressure
- Colloids look "milky" when light is passed through them (Tyndall Effect)
- Suspensions settle if left long enough, and also look milky.