Question 1: The atmosphere contains about 5.2 x1015 t of air. What mass in metri

Question

Question 1: The atmosphere contains about 5.2 x1015 t of air. What mass in metric tons of carbon dioxide is in the atmosphere if the concentration of CO2 is 395 ppm?

Question 2: A person who exercises vigorously several hours a day might take in about 22 m3 of air per day. A tree about 33 m tall and 0.55 m in diameter at its base produces about 84,000 L of oxygen per year. How many people, breathing as described this way, would five such trees supply with oxygen? (Please recall, that 1 m3 = 1000 L, and that normally there's about 20% of oxygen in the air around.)

Explanation / Answer

1)

given concentration = 395 ppm

now

1 ppm is 1 part in 10^6 parts of air

so

395 x 10-6 = mass of C02 / mass of air

given

mass of air = 5.2 x 10^15

so

395 x 10-6 = mass of C02 / 5.2 x 10^15

mass of C02 = 2.054 x 10^12

so

the mass of C02 in the atomosphere is 2.054 x 10^12 t

2)

amount of oxygen produced by 1 tree = 84000 L / year

we know that

1 L = 10-3 m3

so

amount of oxygen produced by 1 tree = 84000 x 10-3 = 84 m3 / year

now

amount of oxygen produced by 5 trees = 84 x 5 = 420 m3 / year

now

amount of oxygen consumed by a person per day = 0.2 x amount of air consumed by a person per day

amount of oxygen consumed by a person per day = 0.2 x 22

amount of oxygen consumed by a person per day = 4.4 m3

now

amount of oxygen consumed by a person per year = 4.4 x 365 = 1606 m3

now

amount of oxygen produced by a tree per year = 420 m3

so

number of people = 420 / 1606 = 0.26

the 5 trees can only provide oxygen for 0.26 people

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