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Chapter 5: Gases.

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Presentation on theme: "Chapter 5: Gases."— Presentation transcript:

1 Chapter 5: Gases

2 Common Properties Uniformly fills any container
Easily compressed compared to liquids and solids Mixes completely with any other gas Exerts a pressure on its surroundings

3 CAN CRUSHING DEMO! Why does this happen?

4 Devices used to measure Pressure (P)
Barometer Used to measure atmospheric pressure Standard atmospheric pressure was determine to be 760 mm Hg but can vary (location or weather)

5 Manometer Used for measuring the pressure inside a container

6 Converting between pressure units: 49 torr = ____ atm
1 standard atmosphere = 1 atm = 760 mm Hg = 760 torr SI Unit for Pressure = N/m2 = pascal (Pa) 1 atm = 101,325 Pa Converting between pressure units: 49 torr = ____ atm 6.4 x 10-2 atm = ______ Pa

7 (Relating Pressure & Volume)
Boyle’s Law (Relating Pressure & Volume) PV = k P1V1 = P2V2

8 (Relating volume & Temperature)
Charles’s Law (Relating volume & Temperature) Volume (V) and Temperature (T) have a direct relationship V1T2 = V2T1

9 Avogadro’s Law Equal volumes of gases at the same temperature and pressure contain the same number of “particles” V1n2 = V2n1 Each ballon holds 1.0 L of a gas at 25 ℃ and 1 atm. Therefore each balloon holds an equal number of particles/moles

10 Example: Suppose we have a 12.2 L sample containing 0.50 mol of O2 gas at 1 atm and 25℃. If all of this O2 were converted to Ozone (O3) at the same temperature and pressure, what would the volume of O3 be?

11 Ideal Gas Law PV = nRT Always watch units when dealing with the ideal gas law All gas laws can be derived from this equation Example: A sample of diborane gas (B2H6), a substance that bursts into flames when exposed to air, has a pressure of 345 torr at a temperature of -15˚C and a volume of 3.48 L. If the conditions are changed so that the temperature is 36˚C and the pressure is 468 torr, what will be the new volume of this sample?

12 Example: A sample containing 0.35 mol of Argon gas at a temperature of 13.0˚C and a pressure of 568 torr is heated to 56.0˚C and a pressure of 897 torr. Calculate the change in volume that occurs

13 GAS STOICHIOMETRY

14 Standard Temperature and Pressure = 0˚C and 1 atm
Molar Volume = 22.4 L at STP Standard Temperature and Pressure = 0˚C and 1 atm Example: A sample of Nitrogen gas has a volume of 1.75 L at STP. How many moles of N2 are present? Quicklime (CaO) is produced by the thermal decomposition of Calcium carbonate (CaCO3). Calculate the volume of CO2 at STP produced from the decomposition of 152 g CaCO3 by the reaction

15 Example: A sample of methane gas having a volume of 2.80 L at 25˚C and 1.65 atm was mixed with a sample of O2 having a volume of 35.0 L at 31˚C and 1.25 atm. The mixture was then ignited to form CO2 and Water. Calculate the volume of CO2 formed at a pressure of 2.50 atm and a temperature of 125˚C

16 Calculating Molar Mass of a Gas
Using PV= nRT Example: The density of a gas was measured at 1.50 atm at 27˚C and found to be 1.95 g/L. Calculate the molar mass of the gas

17 Complete the following problems from textbook pages 219-220
#31,34,35,36,38,39,42,43 To be finished for homework & collected tomorrow


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