CHEMISTRY 161 Chapter 5 www.chem.hawaii.edu/Bil301/welcome.html

Classification of Matter solid liquid gas

1. Gases substances that exist in the gaseous phase under normal atmospheric conditions T = 25oC p = 1 atm

HF, HCl, HBr, HI CO, CO2 CH4, NH3, H2S, PH3 NO, NO2, N2O SO2

Jupiter (H2, He) Io (SO2)

Helix Nebula Orion Nebula

Hindenburg (1937)

molecules/atoms of gas are constantly in motion 2. Pressure Ar molecules/atoms of gas are constantly in motion

Atmospheric Pressure

Standard Atmospheric Pressure 760 mm at 273 K at sea level Torricelli barometer 1 atm = 760 mm Hg = 760 torr pressure of the atmosphere is balanced by pressure exerted by mercury

SI units force pressure = area p = F / A [p] = Nm-2 = kg m-1 s-2 = Pa

pressure measurement manometer

3. Gas Laws 3.1. pressure p versus volume V 3.2. temperature T versus volume V 3.3. volume V versus amount n p, V, T, n

(temperature is constant) 3.1. Boyle’s Law pressure – volume relationship (temperature is constant) Boyle (1627-1691)

p ∞ 1/V

p ∞ 1/V p = const/V p × V = const p1 × V1 = const p2 × V2 = const p1 × V1 = p2 × V2

(pressure is constant) 3.2. Gay-Lussac’s Law temperature – volume relationship (pressure is constant) Gay-Lussac (1778-1850)

V ∞ T

V ∞ T V = const’ ×T V/T = const’ V1 / T1 = const’ V2 / T2 = const V1 / T1 = V2 / T2

(pressure and temperature 3.3. Avogadro’s Law amount – volume relationship (pressure and temperature are constant) Avogadro (1776-1856)

2 H2(g) + O2(g) → 2 H2O(l) n ∞ V

n ∞ V n = const’’ × V n/V = const’’ n1 / V1 = const’’ n1 / V1 = n2 / V2

SUMMARY p ∞ 1/V V ∞ T n ∞ V 3.1. Boyle’s Law 3.2. Gay-Lussac’s Law 3.3. Avogadro’s Law p ∞ 1/V V ∞ T n ∞ V

Homework Chapter 5, p. 153-166 problems