Earth's Atmosphere + Resources (Mock)

How many ‘Evolution of the Atmosphere’ phases were there?

Three

List and describe all three ‘Evolution of the Atmosphere’ phases?

• Phase 1 (Early): Intense volcanic activity released mainly CO₂ water vapour, nitrogen (N₂) , and small amounts of methane (CH₄) and ammonia, similar to Mars/Venus.

• Phase 2 (Oceans & Life): Water vapour condensed to form oceans. CO₂ dissolved into oceans, forming sediments. Algae and plants evolved (~2.7 billion years ago) and used photosynthesis to consume CO₂ and release O₂.

• Phase 3 (Modern): Over millions of years, O₂ increased, allowing complex life, while N₂ built up to ~80%. Carbon became trapped in fossil fuels and sedimentary rocks.

Greenhouse effect - Mechanism?

Mechanism: Short-wavelength radiation from the sun passes through the atmosphere. The Earth absorbs this, warms up, and emits long-wavelength infrared radiation.

Greenhouse effect - Trap?

Trap: Greenhouse gases (CO₂, CH₄, H₂O) absorb this outgoing infrared radiation, trapping heat and warming the lower atmosphere.

Greenhouse effect - Human impact?

Human Impact: Increased burning of fossil fuels and agricultural activity (cows/rice) increases CO₂ and methane, enhancing this effect, leading to climate change, melting ice caps, and extreme weather.

What is the definition of ‘Carbon Footprint’?

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

How can ‘Carbon Footprint’ be reduced?

Reduced by increasing energy efficiency, using renewable energy sources, and taxing or limiting emissions.

What are the sources of ‘Atmosphere Pollutants’?

Combustion of fossil fuels releases gases into the atmosphere.

What are the four ‘key’ pollutants?

Carbon Monoxide (CO), Sulfur Dioxide (SO₂), Nitrogen Oxides (NO_x), Particulates (Soot).

What does ‘Carbon Monoxide, Sulfur Dioxide, Nitrogen Oxides, Particulates (Soot)’ do?

• Carbon Monoxide (CO): Toxic, odourless gas from incomplete combustion.

• Sulfur Dioxide (SO₂): Causes acid rain, from sulfur impurities in fuels.

• Nitrogen Oxides (NO_x): Causes respiratory problems and acid rain, from high-temp engines.

• Particulates (Soot): Causes global dimming and respiratory issues.

What is ‘Potable Water’?

Potable water is water that is safe to drink. It is not pure water (which contains only H₂O molecules) because it contains low levels of dissolved salts and microbes.

Explain the three steps of production (Potable Water)?

1. Selection: Source fresh water (rivers, lakes, underground aquifers) has low levels of dissolved substances.

2. Filtration: Water is passed through wire meshes and sand/gravel beds to remove insoluble solids.

3. Sterilisation: Chlorine gas is bubbled through water to kill microbes. Ozone / UV light can be used.

When is Desalination used (Potable Water)?

Used in areas with limited fresh water (e.g Saudi Arabia) to remove salt from seawater. This is done via distillation or reverse osmosis (using membranes).

Waste water treatment (Potable Water)?

Sewage requires removal of organic matter and harmful microbes through screening, sedimentation, and anaerobic digestion.

RP6 (Required Practical: Water Analysis and Purification) ANALYSIS?

• pH: Use universal indicator to test if the water is neutral (pH 7).

• Dissolved Solids: Weigh an empty evaporating basin, add a known volume of water, evaporate all the water, and reweigh the basin to calculate the mass of remaining solid.

RP6 (Required Practical: Water Analysis and Purification) PURIFICATION (DISTILLATION)?

1. Heat the sea water in a flask until it boils.

2. The water evaporates, leaving salt behind.

3. The steam enters a condenser, cools down, and turns back into a liquid (distilled water).

4. The distillation process can be tested again to check for purity.

The Haber Process (process)?

Process - The gases are passed over an iron catalyst at a high temperature (450∘C) and high pressure (200atm).

The Haber Process (what for)?

An industrial process designed to produce ammonia (NH₃) for use in fertilisers.

Haber Compromise Conditions - Temperature?

Temperature (450∘C): The forward reaction is exothermic, so lower temperatures increase the yield, but would make the reaction too slow. A higher temperature makes it faster but reduces the yield. 450∘C is a "compromise" that provides a decent yield at a reasonable speed.

Haber Compromise Conditions - Pressure?

Pressure (200 atm): Higher pressure increases the yield of ammonia (fewer molecules on the right side) and speeds up the reaction. However, extremely high pressures are expensive and dangerous to maintain. 200 atm is a "compromise" for cost and safety.

Haber Compromise Conditions - Catalyst?

Catalyst (Iron): Speeds up the reaction, allowing it to reach equilibrium faster at a lower temperature, which increases yield, without altering the equilibrium position.

Fertilisers?

Fertilisers (NPK) provide essential elements (Nitrogen, Phosphorus, Potassium) for healthy crop growth.

Fertilisers - Ammonia Products?

Ammonia Products: Ammonia from the Haber process is used to make ammonium salts (e.g ammonium nitrate) by reacting it with nitric acid.

Fertilisers - NPK Fertilisers?

NPK Fertilisers: These formulations contain compounds of all three essential elements.

Fertilisers - Phosphate Rock?

Phosphate Rock: Phosphate rock is insoluble. It is treated with acids to make it soluble:

• Sulfuric Acid: Produces Single Superphosphate (mixture of calcium phosphate and calcium sulfate).

• Phosphoric Acid: Produces Triple Superphosphate (calcium phosphate).

• Nitric Acid: Produces Phosphoric acid and Calcium nitrate.