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Chemistry > Year 9- Environmental Chemistry (core questions) > Flashcards

Year 9- Environmental Chemistry (core questions) Flashcards

1
Q

What is meant by the term atmosphere?

A

Mixture of gases surrounding a planet

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2
Q

What is the proportion of nitrogen in the atmosphere?

A

Around 80%

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3
Q

What is the proportion of oxygen in the atmosphere?

A

Around 20%

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4
Q

What gases are present in the atmosphere in very small proportions?

A

Water vapour, noble gases, carbon dioxide

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5
Q

How has the percentage of carbon dioxide changed from the early atmosphere?

A

Decreased

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6
Q

How has the percentage of oxygen changed from the early atmosphere?

A

Increased

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7
Q

How has the percentage of nitrogen changed from the early atmosphere?

A

Increased

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8
Q

Why did oxygen levels in the atmosphere increase?

A

Photosynthesis

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9
Q

What two groups of living things caused oxygen levels in the atmosphere to increase?

A

Algae and plants

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10
Q

Give two ways in which nitrogen levels in the early atmosphere increased?

A

Volcanoes, oxidation of ammonia

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11
Q

Give three reasons why carbon dioxide levels in the early atmosphere decreased?

A

Photosynthesis, dissolving in oceans, formation of sedimentary rocks and fossil fuels

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12
Q

What are greenhouse gases?

A

Gases in the atmosphere that can absorb infrared radiation (heat)

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13
Q

What are the three main greenhouse gases?

A

Carbon dioxide, water vapour and methane

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14
Q

What is meant by the term greenhouse effect?

A

“Trapping” of thermal energy within the atmosphere

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15
Q

Why is the greenhouse effect important?

A

Maintains global temperatures high enough for life

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16
Q

What is global climate change?

A

Changes in the Earth’s weather patterns due to increased concentration of greenhouse gases

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17
Q

What are four potential effects of global climate change?

A

Increased global mean temperature, melting polar ice caps, rising sea levels, more frequent extreme weather events

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18
Q

What is meant by the term carbon footprint?

A

Total amount of greenhouse gases emitted over the life cycle of a product, service or event

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19
Q

How can the carbon footprint be reduced?

A

Reducing emissions of carbon dioxide and methane

20
Q

What is complete combustion?

A

When a fuel burns in plenty of oxygen

21
Q

What are the products of the complete combustion of hydrocarbons?

A

Carbon dioxide and water

22
Q

What do we use to test for the presence of water?

A

Cobalt chloride paper

23
Q

What change is observed to cobalt chloride paper if water is present?

A

Blue to pink

24
Q

What do we use to test for the presence of carbon dioxide?

A

Bubble through limewater

25
Q

What change is observed to limewater if carbon dioxide is present?

A

Turns cloudy

26
Q

What is incomplete combustion?

A

When a fuel burns in a limited supply of oxygen

27
Q

What are the possible products of incomplete combustion of a hydrocarbon?

A

Carbon dioxide, carbon monoxide, carbon (soot) and water

28
Q

Which pollutants may be released into the atmosphere when a fuel burns?

A

Carbon dioxide, carbon monoxide, particulates, sulfur dioxide, oxides of nitrogen

29
Q

Why is carbon monoxide an environmental concern?

A

Toxic

30
Q

Why is carbon monoxide difficult to detect?

A

Colourless and odourless

31
Q

What environmental problem is caused by particulates?

A

Global dimming

32
Q

What health problem in caused by sulfur dioxide and oxides of nitrogen?

A

Respiratory problems

33
Q

What is crude oil?

A

A fossil fuel formed from ancient plankton buried in mud

34
Q

What does crude oil consist of?

A

A mixture of hydrocarbons with different carbon chain lengths

35
Q

Where is crude oil found?

A

In underground reservoirs

36
Q

How is crude oil formed?

A

High temperature and pressure over millions of years

37
Q

What is meant by the term fraction?

A

A portion of crude oil in which the hydrocarbons have a similar number of carbon atoms

38
Q

What is the first step in fractional distillation in industry?

A

Vaporisation

39
Q

What is the temperature gradient in the fractionating column?

A

Cooler nearer the top

40
Q

How are the fractions of crude oil separated?

A

According to their boiling temperature

41
Q

How is each fraction removed from the fractionating column?

A

By condensation

42
Q

Give the names of 5 useful fuels extracted from crude oil

A

Petrol, diesel, kerosene, heavy fuel oil and liquified petroleum gas (LPG)

43
Q

Give the names of 4 useful products obtained from crude oil

A

Solvents, lubricants, polymers (plastics), detergents

44
Q

How does number of carbon atoms (chain length) affect flammability of fractions of crude oil?

A

Higher chain length = lower flammability

45
Q

How does number of carbon atoms (chain length) affect viscosity of fractions of crude oil?

A

Higher chain length = higher viscosity

46
Q

How does number of carbon atoms (chain length) affect boiling point of fractions of crude oil?

A

Higher chain length = higher boiling point

Chemistry (4 decks)

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