| Question | Answer |
|---|---|
| What is Avogadro's number (Nₐ)? | entities per mole (molecules, atoms, ions, etc.) |
| What is the molar volume of an ideal gas at STP? | 22.4 L/mol at 0 °C and 1 atm |
| What is 1 amu in grams? | g (= 1/12 mass of one C-12 atom) |
| How are empirical and molecular formulae related? | Molecular formula = n × empirical formula, where n = molar mass ÷ empirical formula mass |
| What is the limiting reagent? | The reactant completely consumed first; it determines the theoretical yield |
| Which concentration terms are temperature-independent? | Molality (m), mole fraction (x), mass %, ppm — all mass-based; Molarity and Normality depend on volume (T-dependent) |
| Formula to convert mass % to Molarity? | M = (1000 × d × mass%) / (molar mass × 100), d in g/mL |
| Formula to convert mass % to Molality? | m = (1000 × mass%) / (molar mass × (100 − mass%)) |
| State the Law of Conservation of Mass | Total mass of reactants = total mass of products (Lavoisier, 1789) |
| What is Avogadro's Law? | Equal volumes of gases at the same T and P contain equal numbers of molecules |
Summary: The mole bridges atomic and laboratory scales (1 mol = Nₐ entities = molar mass in grams = 22.4 L at STP for gas). Stoichiometry uses balanced-equation mole ratios to convert between mass, volume, and particle count, with the limiting reagent capping theoretical yield. Concentration terms (M, m, x, N, ppm) each suit different scenarios, and the interconversion formulas linking molarity to molality via density are NEET high-yield.