Global challenges

OCR GCSE ChemistryTopic 6 of 643 lessons

Revision notes for Global challenges in OCR Chemistry A (J248). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

1. Extracting metals using carbonMost metals are found in the Earth's crust as compounds in rocks called ores, often as oxides.
2. Extracting metals by electrolysisMetals that are more reactive than carbon, such as aluminium, hold on to oxygen too strongly for carbon to remove it.
3. Biological methods of metal extractionHigh-grade ores are running out.
4. Rate against equilibrium positionThe Haber process makes ammonia: N2 + 3H2 ⇌ 2NH3.
5. Interpreting graphs of reaction conditionsGraphs help industry choose conditions.
6. Choosing industrial conditionsIndustry chooses conditions that make the most product at the lowest cost, safely.
7. Importance of the Haber process in agriculturePlants need nitrogen to make proteins, but they cannot use the unreactive nitrogen gas in the air.
8. Industrial and laboratory production of fertilisersAmmonium sulfate can be made in a school laboratory or in a factory, and the reaction is the same: ammonia is neutralised by sulfuric acid.
9. Nitrogen, phosphorus and potassium in agriculturePlants need many elements, but nitrogen (N), phosphorus (P) and potassium (K) are needed in the largest amounts.
10. Industrial production of fertilisersA fertiliser factory links several processes together, and each one makes a raw material for the next.
11. Principles of a life-cycle assessmentA life-cycle assessment (LCA) measures the total effect of a material or product on the environment, from the start of its life to the end.
12. Interpreting life-cycle assessment dataInterpreting LCA data means comparing the figures for each product, working out a fair measure, and then deciding which has the lower impact.
13. Recycling a material for a different useRecycling means collecting used materials and processing them so that they can be made into new products instead of being thrown away.
14. Factors affecting decisions on recyclingWhether a material should be recycled depends on weighing the benefits against the costs.
15. Alloys and their usesAn alloy is a mixture of a metal with at least one other element, usually another metal.
16. Corrosion of iron and other metalsCorrosion is the gradual destruction of a metal by reaction with substances in its surroundings.
17. Preventing corrosionRusting can be prevented by keeping oxygen and water away from the iron, which is a physical barrier, or by sacrificial protection.
18. Comparing the properties of materialsDifferent classes of material have different properties, and these can be compared using numbers.
19. Properties of materials and their usesThe material chosen for a job depends on its properties.
20. Functional groups and homologous seriesA functional group is an atom or group of atoms in a molecule that decides how the compound reacts.
21. Naming and drawing the first four membersThe first part of an organic name shows how many carbon atoms are in the chain: meth- is one, eth- is two, prop- is three, but- is four and pent- is…
22. Reactions of alkanes, alkenes and alcoholsCombustion: alkanes and alcohols burn completely in plenty of oxygen to make carbon dioxide and water.
23. Addition polymerisationAlkene molecules contain a C=C double bond.
24. Condensation polymerisationIn condensation polymerisation, monomers join together and, at the same time, a small molecule is lost at every link that forms.
25. Making nylon in the laboratoryNylon is a polyamide made by condensation polymerisation.
26. Addition polymers and their monomersAn addition polymer is made when many small alkene molecules, called monomers, join together in one long chain.
27. DNA and other natural polymersMany important polymers are made by living things.
28. Functional groups and their reactionsA functional group is an atom or group of atoms in an organic molecule that decides how the molecule reacts.
29. Fractional distillation of crude oilCrude oil is a mixture of many hydrocarbons with different chain lengths.
30. Why fractional distillation worksFractional distillation works because the hydrocarbons in crude oil have different boiling points, and the boiling point depends on the size of the…
31. Alkanes in the fractionsThe fractions from crude oil are largely mixtures of hydrocarbons that are alkanes.
32. Crude oil as a source of hydrocarbons and a feedstockCrude oil is a thick, dark liquid found in rocks under the ground or the sea bed.
33. Dependence on hydrocarbons and finite crude oilModern life depends on hydrocarbons from crude oil.
34. Cracking of hydrocarbonsFractional distillation gives more long chain hydrocarbons than we need and fewer short chain ones.
35. Chemical cells and potential differenceA chemical cell uses a chemical reaction to produce a potential difference, which is a voltage.
36. Hydrogen fuel cells and other fuel cellsA fuel cell is a cell that is supplied with a fuel and oxygen from outside, so it keeps producing a potential difference as long as they are supplied.
37. How the early atmosphere formedThe Earth formed about 4.6 billion years ago.
38. How an oxygen-rich atmosphere developedFor roughly the first two billion years there was almost no oxygen in the air.
39. The greenhouse effectThe Sun gives out radiation, mostly visible light with some ultraviolet and infrared.
40. Human causes of climate change and the evidenceSince the Industrial Revolution the concentration of carbon dioxide in the air has risen steadily, from about 280 parts per million to over 400…
41. Effects of carbon dioxide and methane, and how to reduce themCarbon dioxide and methane are greenhouse gases.
42. Atmospheric pollutants and the problems they causeCarbon monoxide forms by incomplete combustion, when a fuel burns without enough oxygen.
43. Methods for increasing the availability of potable waterPotable water is water that is safe to drink.

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