Earth's Atmosphere
The International Space Station orbits The International Space Station orbits earth at an altitude of 350 kilometers, but earth at an altitude of 350 kilometers, but even at this great distance, it still flies through even at this great distance, it still flies through a low-density atmosphere. At 120 km, the a low-density atmosphere. At 120 km, the atmosphere is dense enough to have an atmosphere is dense enough to have an effect upon re-entering space shuttles, yet by effect upon re-entering space shuttles, yet by an altitude of 11 kilometers, nearly 3/4 of the an altitude of 11 kilometers, nearly 3/4 of the atmospheric mass is below you!
atmospheric mass is below you!
The atmosphere consists of a large The atmosphere consists of a large number of gas components, only a few of the number of gas components, only a few of the more common ones are shown in the table. more common ones are shown in the table. The total mass of the atmosphere is The total mass of the atmosphere is estimated to be about 5.1 x 10
estimated to be about 5.1 x 101818 kilograms.kilograms. Scientists compare the abundances of each Scientists compare the abundances of each element in several ways.
element in several ways.
Method 1
Method 1 - In the table, neon is listed- In the table, neon is listed
as '18 ppm' by mass, which means that for as '18 ppm' by mass, which means that for every million particles in the gas there are 18 every million particles in the gas there are 18 neon atoms.
neon atoms.
Method 2
Method 2 - Another way is by stating- Another way is by stating
the gas’s mass fraction. For example, if a the gas’s mass fraction. For example, if a sample of the atmosphere has a mass of 100 sample of the atmosphere has a mass of 100 kilograms, and nitrogen has a mass fraction of kilograms, and nitrogen has a mass fraction of 0.755, that means nitrogen constitutes 100 x 0.755, that means nitrogen constitutes 100 x 0.755 = 75.5 kilograms of the sample.
0.755 = 75.5 kilograms of the sample.
Gas
Gas Component Component Fraction Fraction byby Mass Mass Parts Per Parts Per Million Million Nitrogen Nitrogen 0.755 0.755 781,000781,000 Oxygen Oxygen 0.231 0.231 209,000209,000 Argon Argon 0.013 0.013 9,3409,340 Carbon
Carbon Dioxide Dioxide 0.000582 0.000582 383383 Neon Neon 0.000013 0.000013 1818 Helium Helium 0.0000072 0.0000072 5.25.2 Methane 0.0000094 1.7 Methane 0.0000094 1.7 Krypton Krypton 0.0000033 0.0000033 1.11.1 Hydrogen 0.000000038 0.55 Hydrogen 0.000000038 0.55 Problem 1
Problem 1 - Suppose you have 100 kilograms of air. How many grams of carbon- Suppose you have 100 kilograms of air. How many grams of carbon
dioxide will the sample contain? dioxide will the sample contain?
Problem 2
Problem 2 - What is the mass of Earth's atmosphere in gigatons?- What is the mass of Earth's atmosphere in gigatons?
Problem 3
Problem 3 - What is the total mass of carbon dioxide gas in Earth's atmosphere in units- What is the total mass of carbon dioxide gas in Earth's atmosphere in units
of A)
of A) kilograms? B) kilograms? B) tons? tons? C) gigatons?C) gigatons?
Problem 4
Answer Key
Answer Key
1919
Problem 1
Problem 1 - Suppose you have 100 kilograms of air. How many grams of carbon- Suppose you have 100 kilograms of air. How many grams of carbon
dioxide will the sample contain? dioxide will the sample contain?
Answer:
Answer: 100 kg 100 kg x 0.000582 = x 0.000582 = 0.058 kilograms or0.058 kilograms or 58 grams.58 grams.
Problem 2
Problem 2 - What is the mass of earth's atmosphere in gigatons?- What is the mass of earth's atmosphere in gigatons?
Answer:
Answer: 5.1 5.1 x x 10101818 kilograms x (1 ton/1,000 kilograms) x (1 gigaton/10kilograms x (1 ton/1,000 kilograms) x (1 gigaton/1099tons) =tons) = 5,100,000 gigatons
5,100,000 gigatons..
Problem 3
Problem 3 - What is the total mass of carbon dioxide gas in the atmosphere in units of- What is the total mass of carbon dioxide gas in the atmosphere in units of
A)
A) kilograms? B) kilograms? B) tons? tons? C) C) gigatons?gigatons?
Answer;
Answer; A) A) 5.1 5.1 x x 10101818 kilograms x 0.000582 =kilograms x 0.000582 = 3.0 x 103.0 x 101515 kilograms B) 1 ton = 1,000 kgkilograms B) 1 ton = 1,000 kg so
so 3.0 3.0 x x 10101515 kilograms/1,000 =kilograms/1,000 = 3.0 x 103.0 x 101212 tonstons. . C) 1 C) 1 gigaton = 1.0 gigaton = 1.0 x 10x 1099 tons tons so so 3.03.0 x 10
x 101212 tons/10tons/1099 == 3,000 gigatons3,000 gigatons
Problem 4
Problem 4 - What is the total mass of methane gas in Earth's atmosphere in units of- What is the total mass of methane gas in Earth's atmosphere in units of
gigatons? gigatons?
Answer:
Answer: 5,100,000 5,100,000 gigatons gigatons x x 0.0000094 0.0000094 == 48 gigatons.48 gigatons.
Note to Teacher:
Note to Teacher: Carbon dioxide and methane, along with water vapor, are the threeCarbon dioxide and methane, along with water vapor, are the three
most important greenhouse gases in the atmosphere. Although humans have little most important greenhouse gases in the atmosphere. Although humans have little direct control over the water vapor content, we do have measurable impacts on the direct control over the water vapor content, we do have measurable impacts on the methane and carbon dioxide amounts. An important calculation for the chemistry of the methane and carbon dioxide amounts. An important calculation for the chemistry of the atmosphere is to convert from the volume abundance of a gas, normally cited in parts- atmosphere is to convert from the volume abundance of a gas, normally cited in parts- per-million to an equivalent number of gigatons for the gas. Here is a step-by-step per-million to an equivalent number of gigatons for the gas. Here is a step-by-step method. Let's take the very important gas, carbon dioxide.
method. Let's take the very important gas, carbon dioxide.
It is usually stated as
It is usually stated as having an abundance of having an abundance of 383 parts per million ( 383 383 parts per million ( 383 ppm) byppm) by volume. This means that for a given volume of the atmosphere, every 1 million volume. This means that for a given volume of the atmosphere, every 1 million
particles sampled will have 383 molecules of carbon dioxide. We can also think of this particles sampled will have 383 molecules of carbon dioxide. We can also think of this as if the original volume represented 100%, then carbon dioxide comprises 100% x as if the original volume represented 100%, then carbon dioxide comprises 100% x 383/1 million = 0.0383 % of the volume. To convert this into a mass, we have to use 383/1 million = 0.0383 % of the volume. To convert this into a mass, we have to use the fact that one-mole (6.02 x 10
the fact that one-mole (6.02 x 102323particles) of atmospheric particles has a total massparticles) of atmospheric particles has a total mass of
of 28.97 grams (also called 28.97 AMU). Also, the 28.97 grams (also called 28.97 AMU). Also, the mass of a carbon mass of a carbon dioxide molecule,dioxide molecule, which has 1 carbon and 2 oxygen atoms is
which has 1 carbon and 2 oxygen atoms is 12 AMU + 2 x 12 AMU + 2 x 16 AMU = 44 AMU. This16 AMU = 44 AMU. This means that 1 mole of carbon dioxide will have a mass of 44 grams. So, for the
means that 1 mole of carbon dioxide will have a mass of 44 grams. So, for the
atmosphere, there are 383 carbon dioxide molecules for every 1 million air particles, so atmosphere, there are 383 carbon dioxide molecules for every 1 million air particles, so the mass w