OCR Gateway GCSE Chemistry A: Global challenges (C6) overview

Topic C6 Global challenges of OCR Gateway GCSE Chemistry A (specification J248) is the applied topic: it shows how chemistry is used to make important products, manage resources and understand the environment. It covers industrial processes such as the Haber process, life cycle assessment and recycling, crude oil and its products, the atmosphere and climate change, the pollutants from burning fuels, and how we treat water and extract metals sustainably. This page maps the topic and links to a focused answer page for each part.

The global challenges topics

Improving processes and the Haber process (C6.1)

The Haber process for ammonia, the compromise conditions of temperature and pressure, the iron catalyst and recycling, and the use and importance of NPK fertilisers. See Improving processes and the Haber process.

Life cycle assessment and recycling (C6.1)

The four stages of a life cycle assessment (LCA), the limitations and value judgements involved, and the advantages and disadvantages of recycling and reusing materials including metals. See Life cycle assessment and recycling.

Crude oil and hydrocarbons (C6.2)

Crude oil as a mixture of hydrocarbons, alkanes and their general formula, fractional distillation and the uses of the fractions, and the cracking of long-chain hydrocarbons into alkanes and alkenes. See Crude oil and hydrocarbons.

The atmosphere and greenhouse gases (C6.2)

The composition of the atmosphere, how it evolved over time, the greenhouse gases and the greenhouse effect, and the link between human activity, climate change and the carbon footprint. See The atmosphere and greenhouse gases.

Atmospheric pollutants (C6.2)

Complete and incomplete combustion, the formation of carbon dioxide, carbon monoxide, sulfur dioxide, oxides of nitrogen and particulates, and the harmful effects of each pollutant. See Atmospheric pollutants.

Using the Earth's resources and water (C6.2)

Producing potable water by sedimentation, filtration and sterilisation, desalination by distillation and reverse osmosis, treating waste water, and the sustainable extraction of metals by phytomining and bioleaching. See Using the Earth's resources and water.

How this topic is examined

Topic C6 is assessed on Paper 2 (Foundation, J248/02) or Paper 4 (Higher, J248/04), alongside topics C4, C5 and the C7 practical skills, assuming knowledge of C1 to C3. Each paper is 1 hour 45 minutes, worth 90 marks and 50% of the GCSE. Questions include the Haber process and its compromise conditions, fractional distillation and cracking, the evolution of the atmosphere, the greenhouse effect and climate change, the pollutants from combustion, and water treatment. Many questions ask you to interpret or evaluate data, which is a key skill in this topic. The analysis and purification of water is part of the C7 practical skills.

How to study the global challenges topic

1. Work from the specification statements. Each numbered point is a checklist; questions are written from them.
2. Learn the Haber process and the compromise. Know the conditions and explain why temperature and pressure are a balance of rate and yield.
3. Master crude oil. Learn fractional distillation, the trends down the column, and how and why cracking works.
4. Learn the atmosphere and pollutants. Know the composition, how it evolved, the greenhouse effect, and the pollutants from combustion with their effects.
5. Learn the water and resources content. Know how potable and waste water are treated, and how phytomining and bioleaching work. Use OCR past papers and practise evaluating data.

For the official specification

OCR publishes the full specification (J248), past papers and mark schemes at ocr.org.uk. Always revise from the current specification and OCR's own past papers, because question style is board-specific.