CHEMISTRY 161 Chapter 5

REVISION Boyle’s Law Gay-Lussac’s Law Avogadro’s Law p ∞ 1/V n ∞ V V ∞ T

(1) p ∞ 1/V p × V = const × n × T (2) V ∞ T 1. IDEAL GAS EQUATION (3) n ∞ V V ∞ 1/p V ∞ T V ∞ n V ∞ T × n / p

p × V = const × n × T p × V = R × n × T p × V = n × R × T ieal gas equation

p × V = n × R × T [R] = [p] × [V] / [n] / [T] Pa = N/m 2 m3m3 molK [R] = N × m / mol / K [R] = J / mol / K

R = J / mol / K [R] = J / mol / K ideal gas constant

p × V = n × R × T 2. MOLAR VOLUME What is the volume of 1 mol of a gas at K (0 o C) and 1 atm (101,325 Pa)? standard temperature and pressure (STP) V = 22.4 l

p × V = n × R × T the molar volume at standard pressure and temperature is independent on the gas type V = 22.4 l V m = 22.4 l

3. STOICHIOMETRY NaN 3 (s) → Na(s) + N 2 (g) How many liters of nitrogen gas are produced in the decomposition of 60.0 g sodium azide at 80 o C and 823 torr? 1.Balancing 2.Mole ratios 3.Convert grams into moles 4.Convert moles into liters

4. DENSITY CALCULATION p × V = n × R × T ς = m / V relate the moles (n) to the mass (m) via the molecular weight (M) n = m / M m = n × M V = n × R × T / p ς = p × M / (R × T)

5. DALTON’S LAW Dalton (1801) pure gases gas mixtures (atmospheres)

DALTON’S LAW the total pressure of a gas mixture, p, is the sum of the pressures of the individual gases (partial pressures) at a constant temperature and volume p = p A + p B + p C + ….

p A × V = n A × R × Tp A = n A × R × T / V p B × V = n B × R × T p × V = n × R × T p B = n B × R × T / V p = p A + p B p = (n A + n B ) × R × T / V p × V = n × R × T

p A = n A × R × T / V p × V = (n A + n B ) × R × T p A / p = n A /(n A + n B ) = x A mole fraction x < 1 p A = x A × p

A gas mixture contains 4.46 moles of neon, 0.74 moles of Ar, and 2.15 moles of xenon. Calculate the partial pressure of each gas if the total pressure is 2.0 atm.

2 KClO 3 → 2 KCl + 3 O 2

SUMMARY p × V = n × R × T 1. ideal gas equation R = J / mol / K V m = 22.4 l 2. molar volume

ς = p × M / (R × T) 3. Density of gases 4. Dalton’s Law p = Σ p i i=1 n

Homework Chapter 5, p problems