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The Earth’s early atmosphere contained larger amounts of water vapour and carbon dioxide than it does today - Edexcel - GCSE Chemistry - Question 1 - 2016 - Paper 1
Question 1
The Earth’s early atmosphere contained larger amounts of water vapour and carbon dioxide than it does today. Explain how the amounts of water vapour and carbon dio... show full transcript
Worked Solution & Example Answer:The Earth’s early atmosphere contained larger amounts of water vapour and carbon dioxide than it does today - Edexcel - GCSE Chemistry - Question 1 - 2016 - Paper 1
Step 1
Explain how the amounts of water vapour and carbon dioxide in the Earth’s atmosphere decreased.
Answer
The amounts of water vapour decreased as it condensed and turned into liquid, forming large bodies of water such as oceans, rivers, and lakes. This process removed water vapour from the atmosphere, leading to a significant reduction.
For carbon dioxide, it decreased primarily through two methods: it was absorbed and dissolved in the oceans and lakes, which acted as carbon sinks, and it also incorporated into rocks through various geological processes. Photosynthesis from early plant life further contributed to reducing CO2 levels as plants absorbed carbon dioxide to produce oxygen.
Step 2
Describe how the presence of carbon dioxide in the atmosphere helps to keep the Earth warm.
Answer
Carbon dioxide in the atmosphere acts as a greenhouse gas. It traps heat emitted from the Earth’s surface, preventing it from escaping back into space. This process is known as the greenhouse effect. By absorbing infrared radiation, CO2 helps maintain a stable and warm temperature, which is essential for supporting life on Earth.
Step 3
State a human activity, apart from burning fuels, that has increased the percentage of carbon dioxide in the atmosphere.
Answer
Deforestation is a significant human activity that has increased carbon dioxide levels in the atmosphere. It reduces the number of trees available to absorb CO2 through photosynthesis, thus contributing to higher concentrations of carbon dioxide.