de chemistry – king william high school. …are homogeneous mixtures solute (kool-aid) + solute...
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Chapter 9Solutions
DE Chemistry – King William High School
1. Solutions
…are homogeneous mixtures Solute (Kool-Aid) + solute (water) “like dissolves like”…(polar dissolves
polar & nonpolar dissolves nonpolar) Why does oil not mix with water?
Dissociation equations
Ionic solids break up into their ions in water through a process called hydration (water molecules surround them)
EX: NaCl
EX: CaCl2
2. Electrolytes
Electrolytes dissociate in water and can produce an electric current
IONIC Strong electrolytes completely
dissociate EX: MgSO4
Weak electrolytes partially dissociate EX: NH4OH
Nonelectrolytes
Do NOT separate into ions in water and therefore do NOT conduct an electric current
COVALENT EX: sugar (sucrose)
3. Solubility
Saturated solution - contains the maximum amount of solute that can dissolve in the solvent
Unsaturated solution – is dilute…can hold more solute
Solubility Curves
Temperature & solubility
The hotter a solution is…the more solute you can dissolve
Supersaturated solutions – contains more solute than its solubility allows
Henry’s Law
The solubility of a gas in a liquid (CO2 in your soda) is directly proportional to the pressure of the gas above the liquid
Why does your soda go “flat” after it has been opened?
Solubility rules
Page 294; Table 9.8 EX: K2S
EX: Ca(NO3)2
EX: PbCl2
EX: AlPO4
4. Concentrations
Mass percent =
EX: What is the mass percent of NaOH in a solution prepared by dissolving 30.0 g NaOH in 120.0 g of water?
Molarity
M = mol/L EX: What is the molarity of 60.0 g of
NaOH in 250 mL of solution?
5. Dilution calculations
MV = MV What volume of 18.0 M HCl do you
need to prepare 500 mL of 2.0 M HCl?
6. Properties of solutions
Colloids – are homogenous mixtures where the particles are bigger than solute particles…and they do not “settle” out of solution
Colloid examples on page 305 – table 9.12
Suspensions – heterogeneous mixtures (their particles tend to “settle” out over time
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