Year 10 Science · Unit 2 · Lesson 5
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Learning Goals
Because… chain
Each row on the left is one step in ocean acidification, and the next row is what happens after it. In the box, write the because — the reason that step forces the next one. Do not copy the next step’s words back; explain what makes it follow.
Overall outcome for the Great Barrier Reef:
Real-world context
Research published by the Australian Institute of Marine Science (AIMS) in 2023 reports that the Great Barrier Reef's average surface water pH has fallen from 8.2 (pre-industrial) to approximately 8.1 today, and models project a further fall to 7.9 by 2100 under a high-emission scenario. Coral calcification rates, the speed at which corals build their calcium carbonate skeletons, have already declined by 14% compared to 1990 levels in some monitored reef systems.
(a) Explain the chemical reaction that occurs when CO₂ dissolves in seawater to form carbonic acid. Write a word equation and describe what happens to the H⁺ ions that are released.
(b) Explain why a pH drop from 8.2 to 7.9 threatens coral calcification. Your answer must link the chemistry of lower pH to the availability of carbonate ions (CO₃²⁻) needed to build CaCO₃ skeletons.
1. Catalytic converters in cars reduce nitrogen oxide (NOₓ) emissions. Explain how fitting catalytic converters to all cars in Australia would help reduce acid rain damage to building materials such as limestone. Connect each step: from emission reduction to reduced acid rain to reduced chemical damage.
Wrap Up
In one sentence, what was the main idea of this lesson?