The Cheat Sheet Dashboard
The golden rules examiners love. Scan these first.
Concentration & Temperature
Molarity (M) = mol solute / litre solution → uses volume → changes with temperature (volume expands on heating).
Temperature-independent: mass %, ppm, mole fraction, molality. These use mass, which never changes.
Henry’s Law
p = KH · χ
Partial pressure of a gas is proportional to its mole fraction (χ) in solution.
Higher KH ⇒ lower solubility. And KH increases with temperature ⇒ gases are less soluble in hot water.
Tonicity — the 0.9% NaCl rule
Isotonic = same osmotic pressure as blood = 0.9% (m/V) NaCl (normal saline). Cell stays normal.
Hypertonic (outside stronger): water leaves → cell shrinks (crenation). Hypotonic (outside weaker): water enters → cell swells/bursts.
Interactive Raoult’s Law Graph
Above any liquid mix, some molecules float off as vapour. Raoult’s law says: the more of a liquid you put in, the more of its vapour you get — a neat straight line. When the two liquids don’t get along the same way, the line bends up (positive) or down (negative). Toggle below and watch it bend!
van’t Hoff Factor (i) Calculator
Colligative properties only count how many particles float in the solution, not what they are. Some solutes split into more pieces (salt → 2 ions), some clump together (acetic acid → pairs). The factor i tells you how the particle count changed. Pick a solute and see.
van’t Hoff Factor — Mastery Module
The whole game is counting particles. Each card below is colour-coded by family so your memory groups them: green = no change, blue = splits fully, amber = splits a little, red = clumps together. Flip the cards, study the traps, then test yourself.
The “Trap” Highlighter
⚠️ K₄[Fe(CN)₆] — the coordination sphere does NOT break
It dissociates into 4 K⁺ ions + one intact [Fe(CN)₆]⁴⁻ complex ion — never into separate Fe, C, N. So the count is 4 + 1 = 5 particles ⇒ i = 5. Examiners hope you’ll over-count.
⚠️ Acetic acid — the answer depends on the SOLVENT
In water → dissociation
Partially ionises into ions ⇒ 1 < i < 2. Observed molar mass comes out LOWER than real.
In benzene → association
Two molecules H-bond into a dimer ⇒ i = 0.5. Observed molar mass comes out HIGHER than real.
Mini-Quiz — Instant Recall
Colligative Properties — Quick Formulas
Add any solute to a solvent and four things happen, all depending only on the number of solute particles: the vapour pressure drops, it boils a bit higher, freezes a bit lower, and it can suck in water through a membrane (osmosis).
Before you touch the math, look at the pressure drop. If the pressure drops by a tiny decimal (e.g. 23.80 → 23.77), use the Dilute Shortcut. If the pressure drops by a massive chunk (e.g. 40 → 30), use the Exact Hack.
💡 Always check the pressure drop first, then pick the formula. Small drop → shortcut (denominator P°); big drop → exact (denominator Ps). Get this habit right and RLVP problems become quick, error-free marks. You’ve got this!
1 · Relative Lowering of VP
p° − pp° = χsolute
The drop equals the mole fraction of the solute. (Raoult’s law for a non-volatile solute.)
2 · Elevation of Boiling Point
ΔTb = Kb m
Kb = molal elevation (ebullioscopic) constant. Solution boils higher.
3 · Depression of Freezing Point
ΔTf = Kf m
Kf = molal depression (cryoscopic) constant. Solution freezes lower (why we salt icy roads!).
4 · Osmotic Pressure
π = C R T
Best for macromolecules (proteins/polymers): measured at room temp, gives large, accurate values.
High-Yield Example Flashcards
Every example NCERT gives. Tap a card to flip and reveal the answer.
Easy Explanation — Line by Line
Each key idea of the chapter, in the simplest possible words, with the NEET point to remember.
Exceptions to Remember
All Examples Given in the Chapter
| Category | NCERT examples |
|---|
NCERT Problems — Explained & Solved
Every in-text question and end-of-chapter exercise from the chapter — each one first explained in plain words (what it’s really asking), then solved step by step. Tap a question to open it.
⚖️ Quick Comparisons — Side-by-Side Reference
NEET / JEE loves to test the difference between two almost-identical concepts in Solutions. These 10 side-by-side tables show every common pair. Read each row across; the one you forget is the one they'll ask.
VS Ideal vs Non-ideal solutions
| Property | Ideal | Non-ideal (positive) | Non-ideal (negative) |
|---|---|---|---|
| Obeys Raoult's law | At all compositions | Deviates upward | Deviates downward |
| A-B interactions | Equal to A-A, B-B | Weaker than A-A, B-B | Stronger than A-A, B-B |
| ΔH_mix | 0 | Positive (endothermic) | Negative (exothermic) |
| ΔV_mix | 0 | Positive | Negative |
| Example | Benzene + Toluene | Ethanol + Cyclohexane | HCl + H₂O; Acetone + CHCl₃ |
| Azeotrope | No | Minimum-boiling | Maximum-boiling |
VS Raoult's law vs Henry's law
| Property | Raoult's law | Henry's law |
|---|---|---|
| Statement | p_solvent = x_solvent × p° | p_gas = K_H × x_gas |
| Applies to | Solvent in dilute solutions | Gas dissolving in liquid |
| Constant | p° (pure vapour pressure) | K_H (Henry's constant) |
| Special case | Raoult is a special form of Henry | Henry's law is the limiting law |
VS Concentration units
| Unit | Symbol | Formula | Temperature dependent? |
|---|---|---|---|
| Molarity | M | mol of solute / L of solution | Yes (volume changes) |
| Molality | m | mol of solute / kg of solvent | No |
| Normality | N | g-eq of solute / L of solution | Yes |
| Mole fraction | x | n_i / Σn | No |
| Mass percent | % w/w | (mass solute / mass solution) × 100 | No |
| ppm | ppm | mass solute / mass solution × 10⁶ | No |
Molarity is convenient but molality is preferred for thermal experiments — independent of T.
VS Colligative properties summary
| Property | Formula | Type of change |
|---|---|---|
| Relative VP lowering | Δp/p° = x_solute | Decrease |
| Boiling point elevation | ΔTb = i·Kb·m | Increase |
| Freezing point depression | ΔTf = i·Kf·m | Decrease |
| Osmotic pressure | π = i·CRT | Pressure due to solvent flow |
VS Isotonic vs Hypotonic vs Hypertonic
| Solution type | Compared to cell | Effect on RBC |
|---|---|---|
| Isotonic | Same π | No change |
| Hypotonic | Lower π (more dilute outside) | RBC swells, may burst (haemolysis) |
| Hypertonic | Higher π (more concentrated outside) | RBC shrinks (crenation) |
VS van't Hoff factor i — by solute type
| Solute | i value | Reason |
|---|---|---|
| Glucose, urea | 1 | No dissociation/association |
| NaCl, KCl | 2 (full dissoc) | Splits into 2 ions |
| BaCl₂, K₂SO₄ | 3 | Splits into 3 ions |
| K₄[Fe(CN)₆] | 5 | 5 ions |
| Acetic acid in benzene | 0.5 | Dimerises |
| Weak acid (partial) | 1 + α (n−1) | α = degree of dissociation |
VS Boiling vs Freezing point change
| Property | Boiling point | Freezing point |
|---|---|---|
| Change due to solute | Elevates (rises) | Depresses (falls) |
| Kb (water) | 0.52 K·kg/mol | — |
| Kf (water) | — | 1.86 K·kg/mol |
| Use | Antifreeze, road salt | Antifreeze, salting roads |
| Formula | ΔTb = i·Kb·m | ΔTf = i·Kf·m |
VS Positive vs Negative deviation from Raoult's law
| Property | Positive deviation | Negative deviation |
|---|---|---|
| ΔH_mix | + (endothermic) | − (exothermic) |
| Vapour pressure | Higher than predicted | Lower than predicted |
| A-B interaction | Weaker than A-A, B-B | Stronger than A-A, B-B |
| Example | Ethanol + Acetone, Ethanol + Cyclohexane | Acetone + CHCl₃ (H-bonding); HNO₃ + H₂O |
| Azeotrope | Minimum boiling (boils below components) | Maximum boiling (boils above components) |
VS Azeotrope: Minimum vs Maximum boiling
| Property | Min-boiling | Max-boiling |
|---|---|---|
| Linked to | Positive deviation | Negative deviation |
| Boiling point | Below both pure components | Above both pure components |
| Example | Ethanol-water (95.6% EtOH at 78.1°C) | HCl-water (20.2% HCl at 108.5°C) |
| Separation | Cannot fractionally distil | Cannot fractionally distil |
VS Solid in liquid vs Gas in liquid solubility
| Property | Solid in liquid | Gas in liquid |
|---|---|---|
| Effect of T (typical) | Increases | Decreases |
| Effect of pressure | Negligible | Major (Henry's law) |
| Examples | Salt, sugar in water | O₂, N₂ in water; CO₂ in soda |
Gas dissolution is typically exothermic → higher T disfavours it (Le Chatelier).
50 Previous-Year-Style Questions (PYQ) — Solved
50 NEET/AIPMT-pattern questions covering the whole chapter. Each one is first put in plain words, then solved the exam way: Given → Formula → Step-by-step solution → Answer. Tap any question to open it.
25 JEE Previous-Year-Style Questions — Solved
25 JEE Main / Advanced-pattern questions on Solutions, in the same format: Given → Formula → Step-by-step solution → Answer. Each card shows the topic and the exam year.