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AQA GCSE Chemistry > C13 - The Earth's Atmosphere > Flashcards

C13 - The Earth's Atmosphere Flashcards

1
Q

When was the Earth’s early atmosphere formed?

A

4.6 billion years ago

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2
Q

How do we know what Earth’s early atmosphere was like?

A

gas bubbles trapped in ancient rocks and ice

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3
Q

What are these compounds:
CO2
H2O
N2
CH4
NH3

A

carbon dioxide
water
nitrogen
methane
ammonia

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4
Q

How might the early atmosphere have formed?

A

Volcanoes releasesd CO2 (g), H2O (g), and N2 (g). The H2O (g) condensed as the Earth cooled down which formed precipitation. There were also trace amounts of CH4 (g) and NH3 (g) in the atmosphere. There was little to no oxygen.

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5
Q

What was the percentage of gases in Earth’s early atmosphere?

A

95% carbon dioxide
3.1% nitrogen
1.2% argon
0.2% methane

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6
Q

When do scientists think life began?

A

3.4 billion years ago

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7
Q

When do scientists think algae evolved?

A

2.7 billion years ago

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8
Q

How did oxygen levels increase in the evolving atmosphere?

A

Algae photosynthesized which produced oxygen, O2.

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9
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water → glucose + oxygen

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10
Q

What is the chemical equation for photosynthesis?

A

6CO2 + 6H2O → C6H12O6 + 6O2

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11
Q

Why did the amount of carbon dioxide decrease in the atmosphere?

A

Carbon dioxide was taken in by plants (such as algae) and was converted to glucose and oxygen. The carbon in glucose, C6H12O6, is kept inside the plant material. After millions of years, many organisms were buried under mud and sediment in oceans, rivers, and swamps.

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12
Q

What is coal formed from?

A

Trees and plant matter in swamps. It is classed as a sedimentary rock.

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13
Q

What are crude oil and natural gas formed from?

A

Plankton deposits in mud on ocean seabeds.

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14
Q

What is the scientific name for limestone?

A

calcium carbonate - CaCO3

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15
Q

What happened to methane and ammonia in the atmosphere?

A

They reacted with the oxygen that was formed by algae.

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16
Q

What are the chemical equations for methane and ammonia reacting with oxygen?

A

CH4 + 2O2 → CO2 + 2H2O
4NH3 + 3O2 → 2N2 + 6H2O

17
Q

By what time did our current atmosphere stabilise?

A

200 million years ago

18
Q

What % of gases make up our current atmosphere?

A

78% nitrogen
21% oxygen
0.9% argon
0.04% carbon dioxide
0.1% other gases (e.g. Noble Gases, water vapour)

19
Q

What are the 3 main greenhouse gases?

A

carbon dioxide
methane
water vapour

20
Q

What is the chemical equation for the formation of calcium carbonate (limestone)?

A

CO2 + H2O ⇌ 2H+ + CO32-
Ca2+ + CO32- → CaCO3

21
Q

Why is the Earth heated by greenhouse gases?

A

Greenhouse gases allow short-wavelength electromagnetic radiation (e.g. UV light) to pass through, but it absorbs long-wavelength infrared radiation (thermal). This causes the molecules to vibrate rasing their temperature.

22
Q

What are some consequences of global warming?

A
  • rising sea levels
  • climate change
  • disruption of ecosystems
23
Q

What does carbon footprint mean?

A

The total amount of carbon dioxide and other gases produced by an item over its life cycle.

24
Q

How does CCS work?

CCS - Carbon Capture and Storage

A

Carbon dioxide, formed from fossil fuels, is pumped down to be absorbed by porous rocks; this could be done in old oil fields.

25
Q

What is the advantage of using CCS?

CCS - Carbon Capture and Storage

A

It would reduce the carbon footprint of fossil fuels.

26
Q

What is the disadvantage of using CCS?

CCS - Carbon Capture and Storage

A

Increase the total cost of electricity by 10%.

27
Q

What is one impurity found in fossil fuels?

28
Q

What is formed when sulfur and oxygen react?

A

sulfur dioxide

29
Q

How is acid rain formed?

A

Sulfur dioxide and nitrogen oxides mix with clouds and water to form dilute sulfuric acid and dilute nitric acid.

30
Q

Why do nitrogen oxides rarely form?

A

Nitrogen is a very unreactive element; there must be high temperatures for it to form.

31
Q

What are two gases that form in the incomplete combustion of fossil fuels?

A

CO - carbon monoxide
C - carbon particulates (soot)

32
Q

What are the dangers of acid rain?

A

It can damage buildings (limestone) and corrode metals.

33
Q

What is the cause of smog?

A

nitrogen oxide, NOx

34
Q

What can smog cause?

A

global dimming and respiratory problems

35
Q

How are nitrogen oxides formed?

A

NOx are formed from the oxidization of N2 at high temperatures in combustion.

36
Q

How is sulfur dioxide formed?

A

SO2 is formed from the oxidization of sulfur impurities in fossil fuels.

37
Q

What are the five main pollutants in the atmosphere?

A

CO2 - carbon dioxide
CO - carbon monoxide
C - carbon particulates (soot)
SO2 - sulfur dioxide
NOx - nitrogen oxides

38
Q

What is global dimming?

A

The decrease of sunlight reaching the earth.

AQA GCSE Chemistry (9 decks)

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