Chapter 14 Gases

The Gas Laws 1. Kinetic Theory a. Gas particles do not attract or repel each other each other b. Gas particles are much smaller than the distance between them the distance between them c. Gas particles are in constant random motion motion

d. No kinetic energy is lost during collisions e. All gases have the same average kinetic energy at a given temperature

2. Boyles Law – P 1 V 1 = P 2 V 2 – constant T and pressure is an absolute pressure

3. Charles’s Law – V 1 /T 1 = V 2 /T 2 – constant P & T measured in Kelvin

Plots of V vs. T (Different Gases) Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 407

4. Gay-Lussac’s Law – P1/T1 = P2/T2 constant V

5. Combined Gas Law – P 1 V 1 /T 1 = P 2 V 2 /T 2 Combined Gas Law Combined Gas Law 6. Avogadro’s Principle – equal volumes of gases at the same temperature & pressure contain the same number of particles 7. Molar Volume – the volume occupied by 1 mole of a gas at STP (standard temperature & pressure) = 22.4 L 8. STP = 0 O C & 1 atmosphere

Molar Volume Timberlake, Chemistry 7 th Edition, page 268

The Ideal Gas Law 1. Ideal Gas – behaves according to the Kinetic Theory and obeys the various gas laws (Boyles, etc) 2. Ideal Gas Law – PV = NRT where n = the number of moles and R = ideal gas law constant 3. A lower temperature and higher pressure cause a gas to behave less like an ideal gas (real gas)

4. The larger the gas molecule – the less ideal the behavior 5. The more polar the gas molecule – the less ideal the behavior

Gas Stoichiometry