Chemistry of the atmosphere

Question 1

What percentage of oxygen is there in the air?

Answer 1

21%

Question 2

What percentage of nitrogen is there in the air?

Answer 2

78%

Question 3

What percentage of Co2 in the air?

Answer 3

0.04%

Question 4

What percentage of argon is there in the air?

Answer 4

0.9%

Question 5

How can scientists identify the historic proportions of each gas in the air?

Answer 5

-Scientists know the historic composition of the air by analysing the tiny air bubbles trapped in ice cores taken at the poles
-The air bubbles were trapped as the snow and ice was laid down tens of thousands of years ago and provide a snapshot of what our atmosphere was like back then

Question 6

Why is it difficult to gather evidence about the early atmosphere?

Answer 6

It is difficult to gather evidence about the early atmosphere because it happened 4.6 billion years ago

Question 7

What was the surface of the earth originally like?

Answer 7

The surface of the early Earth was molten for millions of years during which time there was no atmosphere surrounding the planet

Question 8

How were land masses formed from the molten surface of the earth?

Answer 8

Eventually, cooling began to take effect and allow for molten materials to slowly solidify forming land masses

Question 9

What formed on the cooled land masses?

Answer 9

Volcanoes

Question 10

Describe the theory of the formation of the early atmosphere?

Answer 10

-volcanoes released gases from the Earth’s interior through violent eruptions
-These eruptions released large amounts of carbon dioxide and water vapour, as well as nitrogen, hydrogen, and other gases which may have included small proportions of ammonia and methane
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Question 11

Why couldn’t the gases escape into space?

Answer 11

Earth’s gravity prevented the gases from escaping into outer space and they formed the early atmosphere

Question 12

How can scientists deduce the gases present in the earths early atmosphere through the earths crust?

Answer 12

Analysis of the minerals in the Earth’s crust enables scientists to deduce the gases present billions of years ago that helped form those minerals

Question 13

Name two planets that currently have the atmosphere of our early atmosphere?

Answer 13

It is thought that the atmosphere at that moment in Earth’s history was similar to that of Venus or Mars today which consist mainly of CO2

Question 14

How much oxygen was present in the earths early atmosphere?

Answer 14

There was little or no oxygen present because there were no plants or vegetation present ti photosynthesise

Question 15

How did oceans form?

Answer 15

-While the surface of the Earth was still very hot the large quantities of water vapour remained in the gaseous state
-When conditions cooled sufficiently, the water vapour later condensed and fell to the surface of the Earth, forming the oceans

Question 16

How was large amounts of Co2 removed from the atmosphere?

Answer 16

-Carbon dioxide is a water soluble gas (it is the gas used in fizzy drinks) and dissolves readily
-When the water vapour condensed large amounts of CO2 dissolved in the oceans

Question 17

How were sediments formed?

Answer 17

-Carbonate substances were precipitated during this process which later formed sediments
-These processes reduced the amount of carbon dioxide in the atmosphere

Question 18

When did algae first evolve?

Answer 18

Algae first evolved around 2.7 billion years ago and during the next billion years or so small green plants began to appear