CHEMCA
EXAM MASTER FORMULA SHEET
Solutions & Colligative Properties
Optimized for JEE Main, Advanced & NEET
1. Henry's Law
Describes the solubility of a gas in a liquid at a constant temperature.
\[ P = K_H \cdot \chi \]
\(P\) = Partial pressure of gas in vapor phase
\(K_H\) = Henry's Law constant (depends on nature of gas and \(T\))
\(\chi\) = Mole fraction of gas in solution
Trend: Solubility of gases decreases with increase in temperature.
2. Liquid-Liquid Solutions
Raoult's Law (Volatile Components):
\[ P_{total} = P_A^\circ \chi_A + P_B^\circ \chi_B \]
\(P_A^\circ, P_B^\circ\) = Vapour pressures of pure components
Ideal Solutions
- • Obey Raoult's Law exactly
- • \(\Delta H_{mix} = 0\)
- • \(\Delta V_{mix} = 0\)
- • Example: Benzene + Toluene
Non-Ideal (Azeotropes)
- • +ve Deviation: \(P_{obs} > P_{Raoult}\), \(\Delta H_{mix} > 0\)
- • -ve Deviation: \(P_{obs} < P_{Raoult}\), \(\Delta H_{mix} < 0\)
- • Azeotropes: Constant boiling mixtures
3. Colligative Properties
Depend only on the number of solute particles, not their nature.
1. RLVP:
\[ \frac{P^\circ - P_s}{P^\circ} = i \cdot \chi_{solute} \]
2. Elevation in B.P.:
\[ \Delta T_b = i \cdot K_b \cdot m \]
\(K_b\) = Ebullioscopic Constant
3. Depression in F.P.:
\[ \Delta T_f = i \cdot K_f \cdot m \]
\(K_f\) = Cryoscopic Constant
4. Osmotic Pressure (\(\pi\)):
\[ \pi = i \cdot C R T \]
\(C\) = Molarity of solution
4. van't Hoff Factor (\(i\))
\[ i = \frac{\text{Observed Colligative Property}}{\text{Calculated Colligative Property}} = \frac{\text{Normal Molar Mass}}{\text{Observed Molar Mass}} \]
Degree of Dissociation (\(\alpha\)):
\[ \alpha = \frac{i - 1}{n - 1} \]
\(n\) = no. of particles after dissociation
Degree of Association (\(\alpha\)):
\[ \alpha = \frac{1 - i}{1 - 1/n} \]
\(n\) = no. of particles associated (e.g., 2 for dimer)
5. Constant Derivations
Cryoscopic Constant (\(K_f\))
\[ K_f = \frac{M \cdot R \cdot T_f^2}{1000 \cdot \Delta H_{fus}} \]
Ebullioscopic Constant (\(K_b\))
\[ K_b = \frac{M \cdot R \cdot T_b^2}{1000 \cdot \Delta H_{vap}} \]
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