🌈 Solutions – Class 12 Chemistry (Detailed Summary)
🧪 1. What is a Solution?
A solution is a homogeneous mixture of two or more substances.
- Solvent 💧: Present in larger amount
- Solute 🧂: Present in smaller amount
🧠 2. Types of Solutions
| Solute | Solvent | Example |
|---|---|---|
| Solid | Liquid | Salt in water 🧂💧 |
| Liquid | Liquid | Alcohol + Water 🍶 |
| Gas | Liquid | CO₂ in soda 🥤 |
| Gas | Gas | Air 🌬️ |
📊 3. Concentration of Solutions
⚖️ Mass Percentage
Mass % = (Mass of solute / Mass of solution) × 100
🍾 Volume Percentage
Volume % = (Volume of solute / Volume of solution) × 100
⚗️ Molarity (M)
M = Moles of solute / Volume of solution (L)
🌡️ Depends on temperature
❄️ Molality (m)
m = Moles of solute / Mass of solvent (kg)
✔️ Temperature independent
🧮 Mole Fraction
XA = nA / (nA + nB)
🧂➡️💧 4. Solubility
- Maximum amount of solute that dissolves at a given temperature
- Solids: solubility ↑ with temperature 🔥📈
- Gases: solubility ↓ with temperature 🔥📉
⚖️ 5. Henry’s Law
Solubility of a gas in a liquid is directly proportional to pressure.
p = KH × x
- Soft drinks 🥤
- Scuba diving 🤿
- High-altitude sickness 🏔️
🌫️ 6. Vapour Pressure & Raoult’s Law
For ideal solutions:
pA = xA × pA0
🌟 7. Ideal Solutions
- Obey Raoult’s law
- No heat change (ΔH = 0)
- No volume change (ΔV = 0)
- Example: Benzene + Toluene
⚠️ 8. Non-Ideal Solutions
- Positive deviation: Ethanol + Acetone 🔺
- Negative deviation: Chloroform + Acetone 🔻
🧊 9. Colligative Properties
- Relative lowering of vapour pressure 🌫️⬇️
- Elevation of boiling point 🔥⬆️
- Depression of freezing point ❄️⬇️
- Osmotic pressure 💉
ΔTb = Kb × m
ΔTf = Kf × m
π = C R T
🧮 10. Van’t Hoff Factor
i = Observed value / Calculated value
Used to correct abnormal molar mass due to association or dissociation ⚠️
📝 Exam Tips
- Use molality in colligative properties ✔️
- Henry’s law → gas solubility 💨
- Practice numericals 🔢
- Write units clearly ✍️