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This question is about gases - Edexcel - GCSE Chemistry - Question 9 - 2022 - Paper 1
Question 9
This question is about gases. (a) When sodium is added to water, hydrogen gas is produced. Which observation shows that a gas has been produced? A a white precipi... show full transcript
Worked Solution & Example Answer:This question is about gases - Edexcel - GCSE Chemistry - Question 9 - 2022 - Paper 1
Step 1
Step 2
Step 3
Calculate the mass of carbon dioxide that has been released.
Answer
To calculate the mass of carbon dioxide released, we first determine the mass of calcium carbonate that has decomposed:
- Start with the initial mass of calcium carbonate: 5.000g.
- The mass of solid remaining after heating is 2.800g.
- Therefore, the mass of carbon dioxide released is:
- To three significant figures, the mass of carbon dioxide released is 2.20g.
Step 4
Explain, using Figure 15, why helium is inert.
Answer
Helium is considered inert because it has a complete outer electron shell, containing two electrons. This filled shell leads to high stability and makes it unlikely for helium to react with other elements or compounds. Hence, it does not readily participate in chemical reactions.
Step 5
State one property of helium, apart from it being inert, that makes it suitable for filling balloons.
Answer
One property of helium that makes it suitable for filling balloons is that it is lighter than air. This causes balloons filled with helium to rise, making them an ideal choice for balloon decorations or celebrations.
Step 6
Explain how the relative amount of each of the gases in Figure 16 has increased or decreased over time.
Answer
The relative amounts of gases such as carbon dioxide and oxygen in the atmosphere have changed significantly due to natural processes and human activities.
- Water Vapor: This has varied with climate changes, removing or adding moisture to the atmosphere over geological time.
- Carbon Dioxide: Initially present in large amounts due to volcanic activity, its levels have decreased significantly because of the absorption by oceans and its utilization in photosynthesis by plants.
- Oxygen: The amount of oxygen has increased over time primarily due to photosynthesis by plants, which produces oxygen as a byproduct. This process allows for a stable increase in atmospheric oxygen, supporting life on Earth.
Overall, human activities like deforestation and fossil fuel burning have altered these balances even further in modern times, impacting the concentrations of these gases.