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).
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
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