This subtopic builds upon acid base concepts introduced in Stage 1 subtopics 5.1, 5.2, and 5.3.

Some gases in the atmosphere, called ‘greenhouse gases’, keep the Earth’s atmosphere warmer than it would be without these gases. This is known as the ‘greenhouse effect’.

• Describe the action of the common greenhouse gases, carbon dioxide and methane, to maintain a steady temperature in the Earth’s atmosphere.

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Simulation: Greenhouse Effect

Animated Notes (use Microsoft Edge) | Video

Anthropogenic increases in greenhouse gases disrupt the thermal balance of the atmosphere.

• Explain the warming associated with global climate change and its consequences for the environment.

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Video: Climate Change

Ocean acidification is caused by the ocean absorbing higher levels of carbon dioxide from the atmosphere.

• Describe and write equations to show how carbon dioxide lowers the pH of the oceans.
• Calculate the pH of solutions given the concentration of H⁺ or OH^–, and vice versa.

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Practice: Calculations (choose pH calculations)

The skeletons and shells of many marine organisms are made of calcium carbonate and are vulnerable to dissolution at low pH.

• Explain, using equilibrium principles, the impact of altering ocean pH on the formation of carbonates.
  
• Write equations for carbonates reacting in acidic conditions.

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Practice: Reaction equations (choose Carbonate neutralisation)