The term 'molecule' was coined by
He proposed the molecular theory of gases
Avogadro's law is
Mathematical form of Avogadro’s Law
Volume is directly proportional to the number of moles at constant T and P
Equal volumes of O₂ and CO₂ at the same temperature and pressure contain:
Application of Avogadro’s Law
Avogadro’s Law relates volume to number of molecules, not atoms or mass
The vapour density of SO₂ is
Calculation of vapour density of sulphur dioxide
Vapour density = Molecular mass / 2; Molecular mass of SO₂ = 64
The ratio of the mass of a certain volume of gas to the mass of the same volume of hydrogen gas is called
Definition of vapour density
This quantity compares a gas to the lightest gas (hydrogen)
The mass of 22.4 litres of oxygen gas at NTP is nearly
Molar mass of oxygen from molar volume
22.4 L at NTP = 1 mole; Molar mass of O₂ = 32 g/mol
Which of the following is NOT a deduction of Avogadro's law?
Identifying non-deductions of Avogadro’s law
Avogadro’s law talks about molecules, not atoms
According to Avogadro's hypothesis, equal volumes of all gases under similar conditions contain equal number of
Core statement of Avogadro's hypothesis
Think about the particles that make up a gas
The vapour density of a gas is 22.4 at NTP. The volume occupied by 22.4 g of gas is
Volume calculation using vapour density
Mol mass = 2×22.4 = 44.8; 22.4g = 0.5 mol; Volume = 0.5 × 22.4 L
The vapour density of a gas is half that of Sulphur dioxide. The molecular mass of the gas is
Finding molecular mass from vapour density
VD of SO₂ = 32; half of that = 16; Molecular mass = 2 × VD
The volume of 1 mole of gas at 273 K and 1 atmospheric pressure is
Molar volume of gas at NTP
Molar volume at NTP (273 K, 1 atm) = 22.4 L = 22400 mL
The volume occupied by 4.4 g of Carbon dioxide is
Molar mass of CO₂ = 44 g; 4.4/44 = 0.1 mol; Volume = 0.1 × 22.4
