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2 (a) Iron reacts with oxygen to form iron oxide - Edexcel - GCSE Chemistry - Question 2 - 2011 - Paper 1
Question 2
2 (a) Iron reacts with oxygen to form iron oxide. Iron wool was placed in the bottom of a test tube: The test tube was then put in a beaker of water as shown in the... show full transcript
Worked Solution & Example Answer:2 (a) Iron reacts with oxygen to form iron oxide - Edexcel - GCSE Chemistry - Question 2 - 2011 - Paper 1
Step 1
Step 2
Explain why the water level in the test tube rose during the experiment.
Answer
The water level in the test tube rose because oxygen in the air reacted with the iron wool. As iron combines with oxygen to form iron oxide, the volume of gas in the test tube decreases, causing the water level to rise to fill the space left by the gases.
Step 3
Calculate the volume of gas that should be present in the test tube at the end of the reaction.
Answer
Initially, the volume of air in the test tube was 10 cm³. Assuming that the reaction consumes some of the air and given that oxygen is approximately 21% of air, the remaining air after the reaction can be calculated:
Volume of air remaining = 10 cm³ × (79/100) = 7.9 cm³
Thus, the volume of gas that should be present in the test tube at the end of the reaction is approximately 7.9 cm³.
Step 4
Step 5
Explain how the use of fossil fuels affects the composition of the atmosphere.
Answer
The combustion of fossil fuels releases carbon dioxide into the atmosphere, which increases greenhouse gas concentrations. This can lead to global warming and climate change. Additionally, burning fossil fuels can produce pollutants that affect air quality, contributing to health issues and environmental damage.