Properties of Solutions
World B — Acids, Bases & Solutions
18.A — COMPONENTS & TYPES
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R18.01 Solute & Solvent
- Solvent: Major component (dissolving medium).
- Solute: Minor component (substance dissolved).
- Together they form a Solution.
R18.02 True Solutions
- Homogeneous mixture at molecular level.
- Particles < 1 nm (cannot be seen).
- Do not settle out over time.
H₂O
VS
C₆H₆
R18.03 Aqueous vs Non-Aqueous
- Aqueous: Solvent is water (Universal solvent).
- Non-Aqueous: Solvent is organic (Alcohol, Benzene).
- "Like dissolves like" (Polar vs Non-polar).
R18.04 Solid Solutions
- Solutions aren't just liquids!
- Solid in Solid: Alloys (Brass = Zn in Cu).
- Gas in Gas: Air (O₂ in N₂).
18.B — COLLOIDS & SUSPENSIONS
R18.05 Suspensions
- Heterogeneous mixture.
- Particles > 1000 nm (visible to eye).
- Settle down when left undisturbed (Sand in water).
R18.06 Colloids & Tyndall Effect
- Heterogeneous, but appears homogeneous.
- Particles 1 nm - 1000 nm (Milk, Fog).
- Scatters light (Tyndall effect).
- Do not settle out.
18.C — SOLUBILITY & SATURATION
R18.07 Saturated Solutions
- Maximum solute dissolved at a given temperature.
- Additional solute falls to the bottom.
- Dynamic equilibrium established.
R18.08 Supersaturation
- Contains more solute than theoretically possible.
- Highly unstable state (created by cooling).
- A seed crystal triggers rapid crystallization.
R18.09 Temperature Effect
- Solid in Liquid: Heating increases solubility.
- Gas in Liquid: Heating decreases solubility (soda goes flat).
R18.10 Gas Solubility (Henry's Law)
- Solubility of a gas is directly proportional to pressure.
- Higher pressure forces more gas into solution.
- Reason soda fizzes when opened.
18.D — CONCENTRATION & PROPERTIES
vs
R18.11 Dilute vs Concentrated
- Qualitative measure of solute amount.
- Quantitative measures: Molarity, Molality, Mole Fraction.
- Mass percentage: (Mass solute / Mass solution) × 100.
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R18.12 Electrolytes
- Substances that form ions in solution.
- Conduct electricity (Salt water, Acids, Bases).
- Non-electrolytes do not ionize (Sugar water).