Water Cycle - Atmosphere (5)
Pre Lab 

   
OBJECTIVES:
  • Exploring components of air.
  • Analyzing the composition of air.
VOCABULARY:
  • argon
  • atmosphere
  • carbon dioxide
  • nitrogen
  • oxygen
MATERIALS:
Students use a pie chart to compare the components of air.

BACKGROUND:

Air takes up space, has weight, is made of a mixture of different gases, and changes with the altitude. The atmosphere is the envelope surrounding the Earth that contains air. Air is a mixture of the following gases: nitrogen, oxygen, argon, carbon dioxide, hydrogen, and various other rare gases.

The percentage of carbon dioxide varies somewhat because of the presence of vegetation. There are also traces of ammonia, hydrogen sulfide, oxides, sulfur dioxide, and other gases. The percentage of dry air does not vary much with location on the earth's surface. However, the pressure of air changes greatly with the altitude. The average pressure at sea level and 45 degrees latitude is 760 mm Hg, at 4.8 Km it is about 400 mm Hg, at 16 Km it is about 40 mm Hg, and at 48 Km it is only 0.1 mm Hg.

PROCEDURE:
  1. You may want students to use the Periodic Table Placemats and find the elements abbreviation. Write the following table on the board:

Nitrogen (N) 78.03
Oxygen (O) 20.99
Argon (Ar) .94
Carbon dioxide (CO2).035 -.04
Hydrogen (H) .01
Neon (Ne) .012
Helium (He) .0005
Krypton (Kr) .0001
Ozone (O3) .00006
Xenon (Xe) .000009

  1. You may want to make a pie chart or bar graph using the data from the table showing the different components of air. Note that only Nitrogen, Oxygen, and Argon can be seen on a normal pie chart.

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