SACE, Stage 2 Chemistry, Topic 1: Monitoring the Environment, Subtopic 1: Global Warming & Climate Change

Natural Greenhouse Gases

Atmospheric CO₂, H₂O, CH₄, NO and O₃.

Greenhouse Gases

Atmospheric natural or synthetic gases that absorb thermal radiation in the infrared section of the electromagnetic spectrum.

Anthropogenic Greenhouse Gases

Atmospheric SF₆, CFCs and HFCs. As well as anthropogenic increases of CO₂, CH₄ and NO.

Anthropogenic

Caused by or originating from human activity, with a focus on environmental pollution and pollutants.

CFCs

Chlorofluorocarbons

HFCs

Hyrdofluorocarbons

Negative impacts of anthropogenic greenhouse gases.

- Polar ice melts: sea level rises

- Glaciers melting: sea level rises

- Expansion of oceans due to warming

- Melting of permafrost: releases more CH₄

- More severe storms/droughts

- Loss of habitat for flora and fauna

The Greenhouse Effect

Some gases in the atmosphere called 'Greenhouse Gases' keep the Earth's atmosphere warmer than it would be without these gases.

Key Ideas

→ Incoming UV rays, (short λ)

→ Absorbed by the Earth

→ Re-radiated as infrared radiation (long λ)

→ Trapped by greenhouse gases

→ Warm the Atmosphere

→ Rate of re-radiation = rate of escape =

steady temperature

Carbonic Acid Formation

CO₂+H₂O⇌H₂CO₃

Carbonic Acid Ionisation

2H₂O+H₂CO₃⇌2H₃O⁺+CO₃²⁻

Effect of increased H₃O⁺ on pH

Lowers the pH, acidifies the solution, makes the solution more acidic

Proton

H⁺, H₃O⁺

pH

=-log[H⁺], =-log[H₃O⁺], =10^(-pH)

pOH

=-log [OH⁻]

pH Scale

Logarithmic scale, in which one pH unit is a 10-fold change in the hydronium concentration.

Water Ionisation

H₂O+H₂O⇌H₃O⁺+OH⁻

Acid

When a solution has a pH of lower than 7, with lower pH corresponding to higher acidity/stronger acid

Base

Solution with a pH of higher than 7, with higher pH values corresponding to more basic/ caustic solutions

Equilibrium Constant

Kc

Effect of temperature on gas solubility

Solubility decreases as the temperature of the solute increases