Gases in the Atmosphere

Question 1

What are the 4 abundant gases in dry air and their percentages?

Answer 1

nitrogen 78%
oxygen 21%
argon 0.93%
carbon dioxide 0.04%

Question 2

What happens when a substance burns?

Answer 2

combustion

the substance reacts with oxygen to form an oxide (oxidation)

can be acidic, neutral or alkaline

Question 3

Describe the combustion of magnesium

Answer 3

burns with white flame, forms white powder (MgO), alkaline when dissolved in water

2Mg (s) + O2 (g) -> 2MgO (s)

Question 4

Describe the combustion of hydrogen

Answer 4

burns easily with pale blue flame, forms water vapour, neutral pH

2H2 (g) + O2 (g) -> 2H2O (g)

Question 5

Describe the combustion of sulfur

Answer 5

burns with pale blue flame, produces sulfur dioxide, acidic when dissolved in water

S (s) + O2 (g) -> SO2 (g)

Question 6

What is thermal decomposition?

Answer 6

the process of breaking something down/decomposing something using heat

Question 7

What does the thermal decomposition of metal carbonates produce?

Answer 7

carbon dioxide

Question 8

Describe the thermal decomposition reaction of copper (ii) carbonate

Answer 8

CuCO2 (s) -> (heat) CuO (s) + CO2 (g)

copper (ii) carbonate is a green powder
copper (ii) oxide is a black powder
carbon dioxide is a colourless gas

Question 9

What is carbon dioxide?

Answer 9

a greenhouse gas that has increasing amounts in the atmosphere, which may contribute to climate change.