Chemistry Of The Atmosphere (paper 2) Flashcards
(42 cards)
What are the proportions of gases in the Earth’s atmosphere today?
Approximately 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, small amounts of argon and other noble gases, water vapour varies depending on weather conditions.
How was the early atmosphere different from today’s atmosphere?
The early atmosphere was mainly made up of carbon dioxide (very high levels), water vapour, small amounts of ammonia and methane, and no oxygen. This atmosphere was similar to the atmospheres of Mars and Venus today.
How did the levels of carbon dioxide in the atmosphere decrease over time?
Carbon dioxide levels decreased due to:
1. Photosynthesis: Algae and plants absorbed CO₂ and released oxygen.
2. Dissolving in oceans: CO₂ dissolved in oceans and formed carbonates, which were locked into sedimentary rocks.
3. Formation of fossil fuels: Marine organisms used carbon to form shells; when they died, carbon was trapped in limestone, coal, and crude oil.
How did oxygen levels increase in the atmosphere?
Oxygen was produced by photosynthesis from cyanobacteria (algae) and later plants. Over time, oxygen built up in the atmosphere, allowing aerobic organisms to evolve.
Photosynthesis word equation: Carbon dioxide + water → glucose + oxygen
What is the greenhouse effect?
The greenhouse effect is the natural process by which greenhouse gases trap heat in the Earth’s atmosphere.
How it works:
1. Short-wave radiation from the Sun passes through the atmosphere.
2. The Earth’s surface absorbs this energy and re-emits it as long-wave infrared radiation.
3. Greenhouse gases absorb this infrared radiation and re-radiate it in all directions, warming the atmosphere.
What are the main greenhouse gases and their sources?
Carbon dioxide: From burning fossil fuels, deforestation (less photosynthesis).
Methane: From agriculture (e.g., cows), landfills, and rice fields.
Water vapour: Naturally present and increases with temperature.
How do human activities increase greenhouse gas concentrations?
Deforestation: Fewer trees means less CO₂ is absorbed.
Burning fossil fuels: Releases large amounts of CO₂.
Agriculture: Produces methane from animal digestion and decaying organic matter
Landfill sites: Decomposition of waste releases methane.
What are the potential consequences of global climate change?
Rising sea levels due to melting ice caps → flooding and erosion. More frequent extreme weather events (storms, droughts).
Changes in rainfall patterns → impact on farming and water supply.
Loss of biodiversity as species can’t adapt quickly. Food and water insecurity in some regions. Health impacts from heatwaves and disease spread.
What are carbon footprints, and how can they be reduced?
Carbon footprint: The total amount of carbon dioxide and other greenhouse gases emitted over the life cycle of a product, person, or event. How to reduce it: Use renewable energy sources (solar, wind). Increase energy efficiency (e.g., insulation). Use public transport, cycle, or walk. Reduce meat and dairy consumption. Plant trees and protect forests.
Why is it difficult to reduce carbon footprints?
Cost of new technology or green alternatives. Political disagreement across countries. Lack of public awareness or willingness to change habits. Reliance on fossil fuels for industry and transport.
What are the main atmospheric pollutants produced by burning fossil fuels?
- Carbon dioxide – from complete combustion. 2. Carbon monoxide – from incomplete combustion (toxic, colourless gas). 3. Particulates – tiny solid particles (soot) that cause global dimming and health problems. 4. Sulfur dioxide (SO₂) – from sulfur in fuels → causes acid rain. 5. Oxides of nitrogen (NOₓ) – from high temperatures in engines → also cause acid rain and respiratory issues.
What are the problems caused by each of these pollutants?
Carbon monoxide: Prevents oxygen transport in blood; can be fatal. Particulates: Damage lungs; contribute to global dimming. Sulfur dioxide and nitrogen oxides: Cause acid rain, which kills plants and aquatic life, erodes buildings, and irritates lungs.
What is the atmosphere?
The layer of gases surrounding the Earth.
What is nitrogen (N₂)?
Makes up approximately 78% of the Earth’s atmosphere.
What is oxygen (O₂)?
Makes up approximately 21% of the atmosphere; essential for respiration.
What is carbon dioxide (CO₂)?
A greenhouse gas produced by burning fossil fuels, respiration, and deforestation.
What is water vapour (H₂O)?
A variable component of the atmosphere; contributes to the greenhouse effect.
What are noble gases?
Group of inert gases in the atmosphere, such as argon, in trace amounts.
What is the early atmosphere?
Earth’s original atmosphere; mostly carbon dioxide, water vapour, with little or no oxygen.
What is volcanic activity?
Process thought to have formed Earth’s early atmosphere by releasing gases.
What is photosynthesis?
Process by which green plants and algae use carbon dioxide and water to make glucose and oxygen.
Equation: CO₂ + H₂O → C₆H₁₂O₆ + O₂
What are algae?
The first organisms to carry out photosynthesis and release oxygen.
What is the greenhouse effect?
The natural process by which greenhouse gases trap infrared radiation and warm the Earth’s atmosphere.
What are greenhouse gases?
Gases that trap heat in the atmosphere, e.g., carbon dioxide, methane, water vapour.
