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Scientists believe that, about 4500 million years ago, the Earth was very much hotter than it is now - Edexcel - GCSE Chemistry - Question 2 - 2012 - Paper 1
Question 2
Scientists believe that, about 4500 million years ago, the Earth was very much hotter than it is now. The atmosphere then was very different from that on Earth today... show full transcript
Worked Solution & Example Answer:Scientists believe that, about 4500 million years ago, the Earth was very much hotter than it is now - Edexcel - GCSE Chemistry - Question 2 - 2012 - Paper 1
Step 1
Explain why it is difficult to be precise about the composition of the Earth’s early atmosphere.
Answer
Determining the exact composition of the Earth's early atmosphere is challenging due to several factors. Firstly, there was no one present at that time to record data (nobody was there). Secondly, there are no written records or measurements from that period, making it difficult to rely on accurate documentation. Additionally, scientists must contend with different and conflicting sources of information from various studies and findings, which may be based on indirect evidence such as ice cores and rock samples that may not provide a complete or reliable picture.
Step 2
How did this affect the composition of the atmosphere?
Answer
As the Earth cooled and oceans formed, the composition of the atmosphere changed significantly. The presence of oceans likely led to a reduction in the amount of water vapor and carbon dioxide in the atmosphere, as these gases were absorbed by the oceans. This process contributed to the stabilization of atmospheric conditions and set the stage for further developments in the Earth’s environment.
Step 3
Explain how the growth of these plants affected the composition of the atmosphere.
Answer
The growth of the first plants approximately 400 million years ago had a profound impact on the Earth's atmosphere. Plants undergo photosynthesis, a process that utilizes carbon dioxide and releases oxygen. Thus, as plants thrived, they absorbed significant amounts of carbon dioxide from the atmosphere and increased the levels of oxygen. This shift not only contributed to making the atmosphere more hospitable to a variety of life forms but also initiated a fundamental change in the composition of the atmosphere.
Step 4