Year 10 Science · Unit 2 · Lesson 16

Chemical Reactions and the Environment

Challenge Worksheet

Name

Date

Class

Learning Goals

Predict the impact of a large-scale energy transition using multi-factor reasoning.
Evaluate what "true zero-carbon" requires and why infrastructure and hydrogen source matter.
Apply knowledge of combustion chemistry and carbon cycles to an extended what-if scenario.

Go Deeper

What if…?

Scenario

It is 2040. The Australian government has replaced every petrol-powered vehicle on the road with hydrogen fuel cell vehicles. The combustion equation for hydrogen is: 2H₂ + O₂ → 2H₂O. All 20 million vehicles now emit only water vapour from their exhausts. However, 70% of the hydrogen used is produced by steam methane reforming (natural gas + steam → hydrogen + CO₂), while 30% is produced by electrolysis using solar power.

Using what you know from this lesson, predict and explain what would happen to Australia's transport CO₂ emissions, total water vapour production, infrastructure challenges, and whether this fleet is truly "zero-carbon". Use specific chemical knowledge in your answer, refer to equations, reaction types, and the source of hydrogen where relevant.

Challenge 4 marks

Show What You Know

1. Australia's Great Barrier Reef faces threats from both ocean warming and ocean acidification. Explain how a single chemical process, burning fossil fuels, contributes to both threats. Include at least one chemical equation in your answer.

Challenge 3 marks

2. PLA (polylactic acid) bioplastic is made from corn starch and is marketed as "compostable". However, PLA only breaks down in industrial composting facilities at 60°C, not in home compost bins or ocean environments. Evaluate whether PLA deserves to be called "biodegradable" based on what you know about decomposition reactions and environmental conditions.

Challenge 3 marks

Wrap Up

In one sentence, explain why solving an environmental chemistry problem (such as CO₂ emissions) by switching fuels can create new chemistry problems if the full reaction chain is not considered.