Gases

Drill Name the following:   1. HSO4 -1 __________   2. OH-1 __________   3. ClO3 -1 __________   4. C2H3O2 -1 __________   5. OCN-1 __________

Drill Name the following:   1. HSO4 -1 bisulfate or hydrogen sulfate   2. OH-1 hydroxide   3. ClO3 -1 chlorate   4. C2H3O2 -1 acetate   5. OCN-1 cyanate

Objectives iWBAT

Calculate the partial pressure of a gas List, and distinguish between, each postulate

of the KMT Explain the difference between a “real” and

“ideal” gas. Solve collecting gas over water calculations

Partial Pressure Video

http://youtu.be/pgTTKYhqQY0

Partial Pressure

A balloon contains 0.2 moles of nitrogen and 0.5 moles of oxygen. If the total pressure in the balloon is 2.0 atm, what is the partial pressure of oxygen?

Partial Pressure Px = PTotal ( nx / nTotal )Px

= 2.0 atm (0.5 moles/0.7 moles) = 1.4 atm

Collect Gas over Water

http://youtu.be/E5NBZgQ5cl0

Collect Gas Over Water

193 mL of O2 was collected over water on a day when the atmospheric pressure was 762 mmHg. The temperature of the water was 23.0 o C. How many grams of oxygen were collected?

Use Dalton's law and the vapor pressure of water at 23.0 o C to correct the pressure to units of atmospheres.PT = P oxygen +P waterConvert the corrected pressure to atmospheres.Use the ideal gas law to find out how many moles of gas were produced:PV = nRTUse the number of moles and the molecular weight of oxygen to find out how many grams of oxygen were collected.

Kinetic Molecular Theory

http://youtu.be/D2-DtoSQ1Rc

Kinetic Molecular Theory

For IDEAL GASES

1. Volume of individual particles is zero.2. Collisions of particles with container walls

cause pressure exerted by gas.3. Particles exert no forces on each other.

4. Average kinetic energy Kelvin temperature of a gas.

The Meaning of Temperature

(KE)32avg RT

Kelvin temperature is an index of the random motions of gas particles of a gas (higher T means greater motion.)

Real Gases vs Ideal Gases

http://youtu.be/0i2pfnTDEoI

Real Gases

Must correct ideal gas behavior when at high pressure (smaller volume) and low temperature (attractive forces become important).

Figure 5.28Volume Taken up by Gas Particles

Real Gases

[ ]P a V nb nRTobs2( / ) n V

corrected pressurecorrected pressure corrected volumecorrected volume

PPidealideal VVidealideal

Problems to Try

(8th edition) 7,9,13,17,20, 22, 23, 24, 27, 29, 31, 34, 37, 41, 42, 44, 45, 48, 50, 51, 54, 59, 61, 67, 68, 71, 73, 83, 85

(10th edition) P. 232 # 22, p. 234-235 # 62-84 even

Wrap Up What are the conditions that make a gas

“real”? The van der Waals equation accounts for

which differences between real and ideal gases?

Figure 5.24Plots of PV/nRT Versus P for Several Gases (200 K)