Ch10_F15_3 - Chapter 10 Gases 1 2 3 4 5 6 7 8 9 Characteristics of Gases Gas Pressure and Its Measurement The Gas Laws Ideal Gas Law Applications Gas

Ch10_F15_3 - Chapter 10 Gases 1 2 3 4 5 6 7 8 9...

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1 Chapter 10 Gases 1. Characteristics of Gases 2. Gas Pressure and Its Measurement 3. The Gas Laws 4. Ideal Gas Law 5. Applications 6. Gas Mixtures 7. Kinetic-Molecular Theory 8. Effusion and Diffusion 9. Non-Ideal Gases 2 Some Examples of Gases Global Biogeochemical Cycles of Gaseous Species Elements •monoatomic (Noble gases): He, Ne, Ar, Kr, Xe, Rn •molecular (homonuclear diatomics): H 2 , O 2 , N 2 , F 2 , Cl 2 Other gases (molecular): CH 4 , NO 2 , NO, N 2 O, CO 2 , NH 3 , HCl Vapors (liquids with boiling points above room temperature): H 2 O, HNO 3 3 Gases occupy the full volume of their containers. Gas volume, pressure, and temperature are interdependent. Gases have low densities and viscosities. Gases are highly miscible and always form homogeneous mixtures with other gases. 1. Characteristics of Gases
2 Units: areaonacceleratimassareaforcepressure×===kg×(m / s2)m2=kgm×s2=pascal =Pa1 atm = 760 mm Hg = 760 torr = 1.013 ×105Pa = 101.3 kPa = 1.013 bar Example:If a weatherman says that atmospheric pressure is 29.12 inches of mercury, what is it in torr? SI derived unit 2. Gas Pressure and Its Measurement 6
3 7 Manometers • The pressure of a gas in an enclosed volume can be measured with a manometer . • A manometer consists of a volume (a bulb) of gas attached to a U-tube (or J-tube) containing Hg. – There are two types of manometers: 1. closed-end U-tube absolute pressure measurement 8 2. open-end P gas = P atm P gas < P atm P gas = P atm - P Δ h P gas > P atm P gas = P atm + P Δ h relative pressure measurement 9 Boyle s Law 2 2 1 1 V P V P constant PV P 1 constant V P 1 V = = × = n, T constant Put more pressure on something and it gets smaller. 3. The Gas Laws At constant temperature, the volume of a fixed quantity of gas is inversely proportional to its pressure. Robert Boyle (1662)
4 P Hg

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