KTUYSBeta
Log inSign up

Cheat sheet · Class 11 · CBSE · Science Chemistry

Some Basic Concepts of Chemistry cheat sheet

The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.

CBSE Class 11 · Chemistry

Cheat sheet

Chapter 1Some Basic Concepts of Chemistry

1 mole = 6.022 × 10²³ particles = molar mass in grams = 22.4 L of gas at STP.

1. Mole Concept

n=mM=NNAn = \dfrac{m}{M} = \dfrac{N}{N_A}
NA=6.022×1023 mol−1N_A = 6.022\times10^{23}\ \text{mol}^{-1}

Molar volume of an ideal gas at STP (273 K, 1 bar) is 22.7 L; older texts use 22.4 L at 1 atm.

2. Laws of Chemical Combination

  • Conservation of mass (Lavoisier).
  • Definite proportions (Proust): a compound always has the same elements in the same mass ratio.
  • Multiple proportions (Dalton): masses of B combining with fixed mass of A are in simple ratios.
  • Gay Lussac: gases combine in simple volume ratios.
  • Avogadro: equal volumes of gases at same T, P contain equal numbers of molecules.

3. Concentration Terms

TermFormulaDepends on T?
Mass %mass of solutemass of solution×100\dfrac{\text{mass of solute}}{\text{mass of solution}}\times100No
Mole fractionxA=nAnA+nBx_A = \dfrac{n_A}{n_A + n_B}No
Molarity (M)moles of solutelitres of solution\dfrac{\text{moles of solute}}{\text{litres of solution}}Yes
Molality (m)moles of solutekg of solvent\dfrac{\text{moles of solute}}{\text{kg of solvent}}No

4. Formulae

  • Empirical formula: simplest whole-number ratio of atoms.
  • Molecular formula = n × empirical formula, n = molar mass / empirical formula mass.

Steps: % → divide by atomic mass → divide by smallest → whole numbers.

5. Stoichiometry

  • Balance the equation first.
  • Limiting reagent: reactant used up first; it decides the amount of product.
  • Percentage yield = actual / theoretical × 100.

6. Key Points

  • 1 amu (u) = 1/12 mass of a C-12 atom.
  • Significant figures: same rules as physics.
  • Molarity changes with temperature; molality does not.
  • Dilution: M₁V₁ = M₂V₂.

Remember: n = m/M = N/N_A | M vs m | limiting reagent | empirical formula

Some Basic Concepts of Chemistry: questions and notes

More Class 11 · CBSE · Science Chemistry cheat sheets

Practise Some Basic Concepts of Chemistry

Sign up free to practise the full chapter. Questions you get wrong come back until you've mastered them.

Start practising free

Free to start · No credit card needed