gases in the atmosphere (38-40) (paper 1)

Question 1

what are the most prominent gases in the atmosphere

Answer 1

• nitrogen
• oxygen

Question 2

what percentage of air is nitrogen

Answer 2

78%

Question 3

what percentage of air is oxygen

Answer 3

21%

Question 4

what percentage of air is argon

Answer 4

1%

Question 5

what percentage of air is carbon dioxide

Answer 5

0.04%

Question 6

how can you investigate the proportion of oxygen in the atmosphere

Answer 6

using iron ~ rusts to remove oxygen from air

Question 7

explain how iron can be used to investigate the proportion of oxygen in the atmophere

Answer 7

• soak iron wool in acetic acid & put in measuring cylinder
• invert into a beaker of water
• record starting position of water on cylinder
• level of water will rise because iron reacts with water
• leave about a week
• record finishing position
• ((start volume - final volume) / start volume) x 100

Question 8

what is the formula for percentage of oxygen in air from the iron practicle

Answer 8

((start volume - final volume) / start volume) x 100

Question 9

give three examples of elements that reacts with oxygen in air

Answer 9

• magnesium
• hydrogen
• sulfur

Question 10

how does magnesium react with oxygen in the atmosphere

Answer 10

• magnesium burns with a bright white flame in air
• white powder is formed = magnesium oxide
• magnesium oxide powder is slightly alkaline when in water

Question 11

how does hydrogen react with oxygen in the atmosphere

Answer 11

• burns very easily, can explode
• almost invisble pale blue flame ~ product is water

Question 12

how does sulfur react with oxygen in the atmosphere

Answer 12

• burns with a pale blue flame = sulfur dioxide
• acidic when in water

Question 13

what is thermal decomposition

Answer 13

when a substance breaks down into simpler substances when heated

Question 14

what is produced when you heat metal carbonate

Answer 14

• carbon dioxide
• metal oxide

Question 15

what colour is copper (II) carbonate

Answer 15

green powder

Question 16

when is produced when copper (II) carbonate is thermally decomposed

Answer 16

• carbon dioxide
• copper (II) oxide

Question 17

what is the word equation for the thermal decomposition of copper (II) carbonate

Answer 17

copper (II) carbonate -> copper oxide + carbon dioxide

Question 18

what is the chemical equation for the thermal decomposition of copper (II) carbonate

Answer 18

CuCO3(s) -> CuO(s) + CO2(g)

Question 19

how can you test is copper (II) carbonate has effectively thermally decomposed

Answer 19

collect the gas let off and test it for carbon dioxide

Question 20

what type of gas is carbon dioxide

Answer 20

a greenhouse gas

Question 21

how is Earth’s temperature created

Answer 21

by the balance of the heat from the sun and the heat Earth radiates back out to space

Question 22

what is meant by the term greenhouse gas

Answer 22

a gas that absorbs most of the heat that would normally be radiated out into space and re-radiate it in all directions

Question 23

what effects the amount of carbon dioxide in the atmosphere

Answer 23

human activity

Question 24

give examples of how human activity can affect carbon dioxide levels

Answer 24

• deforestation
• burning fossil fuels

Question 25

what does the build up of CO2 suggest is happening

Answer 25

more CO2 is being released into the air faster than it’s being removed

Question 26

what gas is supposely linked to climate change

Answer 26

carbon dioxide