Download presentation
Presentation is loading. Please wait.
Published byCory Stevens Modified over 9 years ago
1
1 Chapter 5: GASES
2
2 In this chapter we will: Define units of pressure and volume Explore the properties of gases Relate how the pressure, volume, and temperature of gases are related
3
3 Characteristics of Gases Uniformly fills any container. Are highly compressible Mixes completely with any other gas Exert pressure on its surroundings.
4
4 Pressure ] Pressure is the force acting on an object per unit area: P = F/A ] Gravity exerts a pressure on the earth’s atmosphere
5
5 Pressure ] The pressure of a 1 m 2 column of air on earth exerts a pressure of about 100 kPa
6
6 Units of Pressure SI units = Newton/meter 2 = 1 Pascal (Pa) 101,325 Pa = 101.325 kPa = 1 atmosphere = 1 atm 1 atm = 760 mm Hg = 760 torr
7
7 Pressure Atmospheric Pressure and the Barometer Atmospheric pressure is measured with a barometer. Standard atmospheric pressure is the pressure required to support 760 mm of Hg in a column
8
8 Units of Pressure The manometer above is another tool used to measure pressure. How would you measure how much pressure is being exerted on the column of mercury?
9
9 Gas Laws: Boyle’s Law The volume of a fixed quantity of gas is inversely proportional to its pressure Pressure Volume = Constant (T = constant) P 1 V 1 = P 2 V 2 (T = constant) V 1/P (T = constant)
10
10 Gas Laws: Boyle’s Law
11
11 Gas Laws: Charles’s Law The volume of a gas is directly proportional to temperature V = constant T (P = constant) V/T = constant
12
12 Gas Laws: Charles’s Law The plot of V vs. T is a straight line. What does that tell us about the relationship between V and T?
13
13 Gay-Lussac’s Law Gas Laws: Gay-Lussac’s Law Gay-Lussac’s Law of Combining Volumes: at a given T and P the volume of gases which react are small whole number ratios.
14
14 Gas Laws: Avogadro’s Law For a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas V = constant n n = number of moles of gas 22.4 L of any gas at 0° C contains 6.02x10 23 gas molecules
15
15 The Meaning of Temperature Temperature measures the average kinetic energy of atoms (higher T means greater motion.) We use the Kelvin temperature scale as an index of the random motions of gas particles.
16
16 Standard Temperature and Pressure “STP” P = 1 atm T = 0 C = 273 K The molar volume of an ideal gas is 22.42 liters at STP
17
17 The Ideal Gas Law An equation of state for a gas. “state” is the condition of the gas at a given time. PV = nRT R = Ideal Gas constant = 0.08206 L atm mol P = pressure in atm V = volume in liters n = moles T = temperature in Kelvins
18
18 The Ideal Gas Law Sample Exercise: A sample of H 2 has a volume of 8.56 L at a temperature of 0° C and a pressure of 1.5 atm. Calculate the moles of H 2 molecules present in this gas sample.
19
19 The Ideal Gas Law Sample Exercise 2: A sample of gas contains 0.35 mol of argon gas at a temperature of 13°C and a pressure of 568 torr is heated to 56°C and a pressure of 897 torr. Calculate the change in volume that occurs.
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.