$word_{count}$: 200

Ideal gas law: PV = nRT. R = 0.0821 L.$\frac{atm}{mol.K}$ = 8.314 $\frac{J}{mol.K}$ = 1.987 $\frac{cal}{mol.K}$. At STP (0 C = 273 K, 1 atm): $V_{molar}$ = 22.4 L/mol. Density of gas: d = $\frac{PM}{RT}$ = M/22.4 (at STP). For mixtures: $M_{avg}$ = sum($x_i$ $M_i$) = sum$\frac{n_i M_i}{sum}$($n_i$). Dalton's law: $P_{total}$ = sum($P_i$); $P_i$ = $x_i$ $P_{total}$. Graham's law: rate of effusion proportional to 1/sqrt(M). Gay-Lussac's law of combining volumes: at same T,P, gas volumes combine in simple ratios. Avogadro's law: V proportional to n at constant T,P. Common calculations: (1) Given mass, find gas volume at STP. (2) Given gas collected over water, subtract water vapour pressure. (3) Given mixture composition, find average molar mass. (4) Eudiometry: combustion of gaseous mixture, measure volume changes.