GCSE AQA Chemistry Causes of Atmospheric Pollution: This question is about the Earth

Question

This question is about the Earth's atmosphere.

The Earth’s early atmosphere was a mixture of gases. One theory is that the Earth’s early atmosphere had the composition shown in Table 4.

Table 4

Gas                             Percentage in Earth's early atmosphere (%)
Carbon dioxide                96
Nitrogen                         3.5
Oxygen                          a trace
Other gases including methane, ammonia, hydrogen and water vapour       0.5

5 (a) (i) Amino acids are at the basis of all life processes. The simplest amino acid is glycine, NH₂CH₂COOH. Two scientists, Miller and Urey, showed that they could produce glycine from a mixture of methane, ammonia, hydrogen and water. Miller and Urey concluded that this is how life was formed on Earth. Suggest one reason why this conclusion may not be correct.

5 (a) (ii) Give three reasons why the percentage of carbon dioxide in the Earth’s atmosphere today is less than the percentage of carbon dioxide in the Earth’s early atmosphere.

5 (b) Table 5 shows the boiling points of some gases in the air.

Table 5

Gas                          Boiling point in °C
Nitrogen                          −196
Oxygen                            −183
Carbon dioxide                −79*
Helium                               −269
Neon                               −246
Argon                               −186

*freezes at this temperature

Oxygen from the air is separated by fractional distillation. To do this separation the air is cooled to −200 °C. Most of the gases condense.

5 (b) (i) Name the two gases that would not condense at −200 °C.

5 (b) (ii) Suggest why carbon dioxide is removed before the air is cooled.

5 (b) (iii) The liquid at −200 °C is passed into a fractionating column. Explain why one of the fractions is a mixture of oxygen and one other gas.

5 (c) Oxygen is used in the production of steel. Cast iron from a blast furnace contains 96% iron and 4% carbon. The stages for the production of steel from cast iron are:
Stage 1 pass oxygen into molten cast iron
Stage 2 add small amounts of other metals.
Explain why each stage is needed in the production of steel.

This question is about the Earth's atmosphere - AQA - GCSE Chemistry - Question 5 - 2017 - Paper 1

Worked Solution & Example Answer:This question is about the Earth's atmosphere - AQA - GCSE Chemistry - Question 5 - 2017 - Paper 1

Suggest one reason why this conclusion may not be correct.

Give three reasons why the percentage of carbon dioxide in the Earth’s atmosphere today is less than the percentage of carbon dioxide in the Earth’s early atmosphere.

Name the two gases that would not condense at −200 °C.

Suggest why carbon dioxide is removed before the air is cooled.

Explain why one of the fractions is a mixture of oxygen and one other gas.

Explain why each stage is needed in the production of steel.

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