The SI fundamental units include meter, second, kelvin, and kilogram. Gram is a derived unit (1/1000 kg).

A homogeneous mixture has uniform composition, like air, which is a mix of gases.

Molar mass of H₂O = 18 g/mol (2 × 1 + 16). Oxygen’s mass = 16 g. Percent = (16/18) × 100 = 88.89%.

Avogadro’s number (6.022 × 10²³) is the number of particles in 1 mole of a substance.

Molar mass of H₂O = 2 × 1 (H) + 16 (O) = 18 g/mol.

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction.

Mass of one C-12 atom = 12 g/mol ÷ 6.022 × 10²³ atoms/mol = 1.992 × 10⁻²³ g.

A compound consists of different atoms chemically bonded in a fixed ratio, like H₂O.

At standard temperature and pressure (0°C, 1 atm), 1 mole of an ideal gas occupies 22.4 liters.

Density is mass per unit volume, calculated as mass divided by volume (g/cm³ or kg/m³).

The limiting reagent is fully consumed first, limiting the reaction’s product yield.

Sodium chloride (NaCl) is a compound, requiring chemical means to separate into Na and Cl, unlike mixtures.

Molar mass of CO₂ = 12 + 2 × 16 = 44 g/mol. Moles = 88 g / 44 g/mol = 2 moles.

The empirical formula is the simplest whole-number ratio of atoms; CH₂O is the simplest form for compounds like glucose.

NaOH molar mass = Na (23) + O (16) + H (1) = 40 g/mol.

1 mole of any substance contains Avogadro’s number (6.022 × 10²³) of particles, whether atoms, molecules, or ions.

Intensive properties, like temperature, do not depend on the amount of substance, unlike extensive properties like mass.

Air is a homogeneous mixture of gases like nitrogen, oxygen, and others, not chemically combined.

The mole measures the number of particles (6.022 × 10²³) in a substance, defined as the SI unit for amount of substance.

1 mole of H₂ contains 2 × 6.022 × 10²³ atoms. O₂ and CO₂ have 2 and 3 atoms per molecule, respectively, and O₃ has 3, but H₂ is diatomic and simpler, still yielding 2 × Avogadro’s number.