Chemistry of the atmosphere

Question 1

Name some human activities that increase greenhouse gases.

Answer 1

Farming cattle / rice farming in paddy fields - releases methane.
The burning of fossil fuels in vehicles - releases CO2.
deforestation’s produces CO2, and reduces its absorption.

Question 2

What are some effects of global warming?

Answer 2

glaciers and polar ice melting, leading to the rise of sea levels.
Extreme weather changes (droughts / floods).
Habitats changing.

Question 3

How were the oceans formed?

Answer 3

As the Earth cooled, the water vapour in the atmosphere condensed, forming oceans.

Question 4

Explain how levels of CO2 decreased.

Answer 4

Absorbtion by oceans - when oceans formed, CO2 was dissolved into them.
Absorbtion by plants and algae - once they evolved, they absorbed some CO2 by photosynthesis.
Carbon was locked away in sedimentry rocks and fossil fuels.

Question 5

How was the carbon locked away?

Answer 5

When organisms die, they fall to the seabed and get buried under layers of sediment. Over millions of years, they become compressed and form sedimentry rocks, oil, and gas (fossil fuels), trapping carbon within them.

Question 6

How did the levels of oxygen increase?

Answer 6

Oxygen was increased by photosynthesis.

6CO2 + 6H2O = C6H12O6 + 6O2

Question 7

Why did nitrogen build up in the atmosphere?

Answer 7

Because it is unreactive.

Question 8

Describe the greenhouse effect.

Answer 8

All particles absorb certain frequencys of radiation. The sun emits short wavelength radiation, which passes through the Earth’s atmosphere. It is absorbed by the Earth’s surface, and re-emitted as long wavelength radiation. This is absorbed by greenhouse gases, which re-radiate it in all directions. This is thermal radiation, and so results in the warming of the Earth’s surface.

Question 9

What is the Earth’s atmosphere?

Answer 9

The layers of gases that surround the Earth. It is 78% nitrogen, 21% oxygen and 1% other gases, such as argon, carbon dioxide and noble gases.

Question 10

Where did the early atmosphere come from?

Answer 10

It is believed that the intense volcanic activity in the first billion years after the Earth was formed gave out the gases that went on to form the early atmosphere and the oceans.

Question 11

What was the early atmosphere made up of?

Answer 11

It was probably mostly carbon dioxide, with virtually no oxygen, like the atmosphere of venus today. Volcanic activity probably also produced nitrogen, as well as water vapour, small amounts of methane, and ammonia.

Question 12

Describe the problems with carbon particulates.

Answer 12

Particles of carbon in the air are caused by the incomplete combustion of carbon containing fuels. They are a problem because they can get stuck in the lungs and cause damage, leading to respiritory problems.

Question 13

What is global dimming and why does it happen?

Answer 13

Global dimming is the reduction in the amount of global direct irradiance reaching the Earth’s surface. It occurs because of carbon particulates.

Question 14

Describe the problems of sulfer dioxide.

Answer 14

When sulfer dioxides (SO2) or oxides of nitrogen (NOx) react with water in the clouds, they form sulferic acid or nitric acid. This falls as acid rain, damaging buildings, harming plants and animals, and making rivers and lakes acidic.

Question 15

What is the chemical formula for sulferic acid?

Answer 15

SO3 + H2O = H2SO4

Question 16

Define what is meant by ‘carbon footprint’.

Answer 16

The carbon footprint is the total amount of carbon dioxide and other greenhouse gases that are emitted over the full life cycle of a product, organism, service or event.

Question 17

Suggest ways to reduce carbon footprint.

Answer 17

Use alternative energy sources.
Reduce car travel.
Improve home insulation.
Reduce, reuse, recycle.
Reduce use of single use plastics.
Conserve electricity and stuff.

Question 18

What are the problems of carbon monoxide?

Answer 18

Carbon monoxide is produced in the incomplete combustion of carbon containing fuels. It binds to haemoglobin in blood, limiting the amount of oxygen carried around the body. It can lead to fainting, coma or even death.
It’s dangerous because it’s colourless, odurless and hard to detect.

Question 19

How do you test for hydrogen?

Answer 19

The squeaky pop test. Light a splint and insert into a test tube of hydrogen. There will be a pop noise.
2H2(g) + O2(g) = 2H2O(g)

Question 20

How do you test for oxygen?

Answer 20

Place a glowing splint in oxygen, and it will relight.

Question 21

How do you test for carbon dioxide?

Answer 21

Bubble carbon dioxide through limewater and it will turn milky-white. This colour is a precipitate of calcium carbonate.
Ca(OH)2(aq) + CO2(g) = CaCO3(s) + H2O(l)

Question 22

How do you test for chlorine gas?

Answer 22

Holding damp blue litmus paper in chlorine gas will bleach the paper, turning it white.

Question 23

How do you test for ammonia?

Answer 23

Holding damp red litmus paper in ammonia will turn the paper blue.