2c-Gases in the atmosphere Flashcards
Question: What are the main gases in Earth’s atmosphere?
Nitrogen (78%)
Oxygen (21%)
Argon (0.9%)
Carbon dioxide (0.04%)
Question: How can you determine the percentage of oxygen in the air using copper?
Heat copper in a tube while passing air over it.
Copper reacts with oxygen to form copper oxide, removing oxygen from the air.
Measure the decrease in air volume to calculate the percentage of oxygen.
Question: What is the equation for the reaction of copper with oxygen?
Answer:2Cu (s) + O₂ (g) → 2CuO (s)
Question: How can you determine the percentage of oxygen using iron or phosphorus?
Answer:
Place iron wool or phosphorus in a closed container of air.
As iron rusts or phosphorus burns, it removes oxygen from the air.
Measure the decrease in air volume to find the percentage of oxygen.
Question: What happens during the combustion of magnesium, hydrogen, and sulfur?
Magnesium: Burns with a bright white flame, forming magnesium oxide (MgO).
Hydrogen: Burns with a pale blue flame, producing water (H₂O).
Sulfur: Burns with a blue flame, forming sulfur dioxide (SO₂).
Question: What is thermal decomposition, and how does it apply to metal carbonates?
Answer: Thermal decomposition is the breakdown of a compound using heat. Example:
Calcium carbonate → Calcium oxide + Carbon dioxideCaCO₃ (s) → CaO (s) + CO₂ (g)
Question: What are the environmental impacts of carbon dioxide?
Answer: Carbon dioxide is a greenhouse gas that traps heat in the atmosphere, contributing to global warming and climate change.
Practical: Investigating the Percentage of Oxygen in the Air
Method:
Pass air over heated copper in a sealed tube.
Measure the decrease in air volume as oxygen reacts with copper.
Practical: Investigating the Percentage of Oxygen in the Air
Results & Conclusion
Results:
Air volume decreases by approximately 21%, indicating the percentage of oxygen.
Conclusion:
Oxygen makes up about 21% of the air.
