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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 th... 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 iron reacts with oxygen in the air, creating iron oxide. As the iron reacts, it consumes the oxygen, leading to a decrease in gas volume inside the test tube. This decrease creates a partial vacuum which causes the water to be drawn up into the tube.
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. At the end of the reaction, the percentage of oxygen remaining in the air is 21%, which means:
Volume of air remaining = 10 cm³ × 79/100 = 7.9 cm³. Thus, the volume of gas that should be present at the end of the reaction is 7.9 cm³.
Step 4
Step 5
Explain how the use of fossil fuels affects the composition of the atmosphere.
Answer
The use of fossil fuels contributes significantly to the increase of carbon dioxide in the atmosphere. When fossil fuels are burned for energy, they release carbon dioxide as a byproduct. This increase in carbon dioxide leads to enhanced greenhouse gas effects, contributing to climate change and altering overall atmospheric composition.