CBSE Class 12–level explanation of Ideal and Non-Ideal Solutions

 CBSE Class 12–level explanation of Ideal and Non-Ideal Solutions, along with examples and a comparative table.

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✅ Ideal Solution

🔹 Definition:

A solution that obeys Raoult’s Law at all concentrations and temperatures is called an ideal solution.

🔹 Raoult’s Law:

For component A and B:

Ptotal = P_A + P_B

• , : partial vapour pressures
• , : vapour pressure of pure components
• , : mole fractions

🔹 Characteristics:

• ΔH_mix = 0 (no heat absorbed or evolved)
• ΔV_mix = 0 (no volume change on mixing)
• No intermolecular force change

🔹 Examples:

• Benzene + Toluene
• n-Hexane + n-Heptane
• Ethyl bromide + Ethyl chloride

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❌ Non-Ideal Solution

🔹 Definition:

A solution that does not obey Raoult’s Law at all concentrations and shows deviations is called a non-ideal solution.

🔹 Types of Deviations:

1. Positive Deviation

   • Weaker A–B interactions
   • ΔH_mix > 0 and ΔV_mix > 0

   🔸 Example:

   • Ethanol + Acetone
   • Ethanol + Cyclohexane

2. Negative Deviation

   • Stronger A–B interactions
   • ΔH_mix < 0 and ΔV_mix < 0

   🔸 Example:

   • HCl + Water
   • Acetone + Chloroform

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📊 Comparison Table:

Property	Ideal Solution	Non-Ideal Solution
Obeys Raoult’s Law	Yes	No
Enthalpy change (ΔHmix)	0	≠ 0 (positive or negative)
Volume change (ΔVmix)	0	≠ 0
Intermolecular forces	A–B = A–A = B–B	A–B ≠ A–A or B–B
Examples	Benzene +                                          Toluene	Acetone + Chloroform, Ethanol                                +                              Water

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