GCSE Chemistry: Atmosphere Composition, Evolution, and Pollution

What are the main gases in the Earth's atmosphere?

Approximately 80% nitrogen and 20% oxygen, with small proportions of other gases like CO2, H2O(g), and noble gases.

What was the composition of the early Earth's atmosphere?

It may have been similar to Mars and Venus, mainly composed of CO2 with little or no O2, and included nitrogen, methane, and ammonia.

What process led to the formation of oceans on Earth?

Water vapor condensed to form oceans, and CO2 dissolved in the water, precipitating carbonates and reducing atmospheric CO2.

How did oxygen levels in the atmosphere increase?

Oxygen was produced by algae and plants through photosynthesis, starting about 2.7 billion years ago.

What is the photosynthesis equation?

6CO2 + 6H2O -(light)-> C6H12O6 + 6O2.

What contributed to the decrease of carbon dioxide in the atmosphere?

Photosynthesis by algae and plants, formation of sedimentary rocks containing carbon, and production of fossil fuels.

What are greenhouse gases?

Gases that maintain Earth's temperature, including water vapor, CO2, and CH4.

What is the greenhouse effect?

The process where electromagnetic radiation from the sun passes through the atmosphere, is absorbed by the Earth, and some heat is re-radiated as infrared radiation, which is then absorbed by greenhouse gases.

What human activities increase greenhouse gas levels?

Driving, consuming electricity, raising livestock, and decay of organic waste in landfills.

What are some potential effects of global climate change?

Extinction of species, rising sea levels, migration due to drought/flooding, and decreased crop yields.

What is a carbon footprint?

The total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, service, or event.

How can the carbon footprint be reduced?

By reducing emissions of CO2 and methane, using less electricity, reducing travel, and planting more trees.

What are common atmospheric pollutants from fuel combustion?

Carbon dioxide, water vapor, carbon monoxide, oxides of nitrogen, solid particles, and unburned hydrocarbons.

What is produced during incomplete combustion?

Solid particles of soot, carbon monoxide, and unburnt fuel.

What are the properties of carbon monoxide?

It is a toxic, colorless, and odorless gas, making it difficult to detect.

What are the effects of sulfur dioxide and oxides of nitrogen?

They cause acid rain and respiratory problems in humans.

What are particulates and their effects?

Solid particles that cause global dimming and health problems in humans.

What is the significance of the time scale of 4.6 billion years in studying the atmosphere?

It limits evidence about the early atmosphere and leads to evolving theories over time.

What role did volcanic activity play in the early atmosphere?

It released gases that formed the early atmosphere and contributed to the buildup of nitrogen.

What is the relationship between algae and atmospheric oxygen levels?

Algae were the first organisms to produce oxygen through photosynthesis, increasing atmospheric oxygen levels.

How does the greenhouse effect contribute to global warming?

It leads to an increase in atmospheric temperatures, which can result in climate change.

What is the impact of human activities on the carbon cycle?

They increase greenhouse gas emissions, contributing to climate change and altering natural carbon processes.

What is the significance of peer-reviewed evidence in climate change discussions?

It provides a scientific basis for understanding climate change, though modeling complex systems remains challenging.

What are the challenges in reducing carbon emissions?

It can be difficult and expensive, and land used for planting trees could alternatively be used for crops.

What is the role of sedimentary rocks in the carbon cycle?

They store carbon and help decrease atmospheric CO2 levels.

What are the main sources of atmospheric pollutants?

Combustion of fossil fuels, industrial processes, and agricultural activities.

What is the effect of global climate change on crop yields?

It may lead to a decrease in crop yields for all major world crops.