Deviations from the Ideal Gas Lawand

Chemistry in the Atmosphere

Chemistry 142 B

Autumn Quarter, 2004

J. B. Callis, Instructor

Lecture #16

Deviations from Ideal behavior for real gases

The effect of intermolecular attractions on measured gas pressure.

The effect ofmolecularvolume onmeasured gasvolume.

The van der Waals equation of state is valid over a wider range of conditions than the ideal gas law:

nRTnbVV

anP

2

2

Where P is the measured pressure, V is the container volume, n is the number of moles of gas and T is the temperature. a and b are the van der Waals constants, specific for each gas.

Problem 16-1:van der Waals Calculation of a Real gas

Problem: A tank of 20.00 liters contains Chlorine gas at a temperature of 20.000C at a pressure of 2.000 atm. if the tank is pressurized to a new volume of 1.000 L and a temperature of 150.00 0C. What is the new pressure using the ideal gas equation, and the van der Waals equation?Plan: Do the calculations according to the ideal gas and vdV eqns.Solution:

n =

Pideal =

PvdV =

Variation of Temperature and Pressure with Altitude

Sources of Air Pollution

• Transportation

• Production of Electricity

Air Pollution from Cars and Trucks

Combustion of petroleum produces CO, CO2, NO and NO2 together with unburned petroleum.

N2 + O2 2 NO; 2 NO + O2 2 NO2

NO2 NO + O (reactive) : O + O2 O3 (ozone)

This net production of ozone then produces other pollutants.

Concentration of Smog Components Over a Day

Air Pollution from Electricity Production by Coal Burning PlantsCoal contains significant quantities of sulfur, which when burned produces sulfur dioxide:

S + O2 SO2;

SO2 can be further oxidized to sulfur trioxide:

2SO2 + O2 2SO3 (ozone)

Sulfur trioxide can combine with moisture to produce the corrosive H2SO4.

Sulfur Dioxide Scrubber Chemistry

Production of Lime: CaCO3 CaO + CO2

Capture of SO2: CaO + SO2 CaSO3

Sulfur Dioxide Scrubber

Answers to Problems: Lecture 16

1. Pideal = 57.745 atm; PvdV = 45.751 atm