CARA'S TIPSNuclear, environmental & industrial chemistry
JAMBWAECNECO
What the syllabus asks
JAMB: Nuclear chemistry (radioactivity, nuclear reactions, half-life, uses), environmental pollution (sources, effects and control), chemical industries (Haber, Contact process, petroleum, local industries)
WAEC: Nuclear chemistry: radioactivity, types and properties of radiations (α, β, γ), nuclear equations, half-life, nuclear fission and fusion, uses and dangers of radioisotopes; environmental chemistry: air pollution (CO, SO₂, oxides of nitrogen, particulates), acid rain, greenhouse effect, ozone depletion, water pollution and treatment; chemical industry: raw materials, Haber and Contact processes,…
NECO: Nuclear chemistry: radioactivity, types and properties of radiations (α, β, γ), nuclear equations, half-life, nuclear fission and fusion, uses and dangers of radioisotopes; environmental chemistry: air pollution (CO, SO₂, oxides of nitrogen, particulates), acid rain, greenhouse effect, ozone depletion, water pollution and treatment; chemical industry: raw materials, Haber and Contact processes,…
What you will learn
- Describe the nature and properties of alpha, beta and gamma radiations.
- Write and balance nuclear equations for alpha and beta decay and for artificial transmutation.
- Define half-life and solve half-life problems, including radiocarbon dating.
- Distinguish between nuclear fission and fusion and state uses and dangers of radioisotopes.
- Identify major air and water pollutants, their sources, effects and control, with Nigerian examples.
- Explain the greenhouse effect, acid rain and ozone depletion.
- Describe the Haber and Contact processes, petroleum refining and other key Nigerian industries, and carry out related calculations.
Key points
- Radioactivity is spontaneous nuclear decay; it is unaffected by temperature or chemical state.
- α = ⁴₂He (most ionising, least penetrating); β = ⁰₋₁e; γ = EM radiation (least ionising, most penetrating).
- Nuclear equations balance A and Z; α: A − 4, Z − 2; β: Z + 1.
- After n half-lives, (½)ⁿ remains; carbon-14 (t½ ≈ 5,730 years) dates once-living material.
- Fission splits heavy nuclei in a controlled chain reaction; fusion joins light nuclei in the sun.
- Radioisotopes are used in medicine, agriculture and industry; handle with tongs, shielding, distance and short exposure.
- CO is poisonous; SO₂ and NO₂ cause acid rain; CO₂ and CH₄ cause the enhanced greenhouse effect; CFCs destroy ozone.
- Water treatment: screening, coagulation (alum), sedimentation, filtration, chlorination.
- Haber: N₂ + 3H₂ ⇌ 2NH₃, iron catalyst, ~450 °C, ~200 atm; Contact: 2SO₂ + O₂ ⇌ 2SO₃, V₂O₅, ~450 °C, 1–2 atm.
- Crude oil is separated by fractional distillation and improved by cracking; soap is made by saponification.
Start here: Radioactivity and the three radiations
In 1896, Henri Becquerel left uranium salts on a wrapped photographic plate and found the plate fogged, though no light had reached it. The uranium was giving out invisible radiation on its own. Marie and Pierre Curie went on to discover polonium and radium. This property is called radioactivity.
Nuclei become unstable when they have too many neutrons, too few neutrons, or are simply too big (most elements beyond lead, Z = 82). Three types of radiation are given out:
| Property | Alpha (α) | Beta (β) | Gamma (γ) |
|---|---|---|---|
| Nature | helium nucleus ⁴₂He | fast electron ⁰₋₁e | electromagnetic wave |
| Charge | +2 | −1 | 0 |
| Relative mass | 4 | about 1/1840 | 0 |
| Penetration | a few cm of air; stopped by paper | stopped by a few mm of aluminium | reduced by several cm of lead or thick concrete |
| Ionising power | highest | moderate | lowest |
| In electric/magnetic field | deflected slightly (heavy) | deflected strongly, opposite way to α | not deflected |
There is a simple pattern: the more strongly a radiation ionises (knocks electrons off atoms), the faster it loses energy and the less it penetrates.
A radiation passes through paper but is stopped by 5 mm of aluminium. It is deflected in a magnetic field. Identify it.
- Passes paper, so it is not alpha.
- Stopped by thin aluminium and deflected, so it is not gamma (gamma is uncharged and very penetrating).
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Practice questions
- iron
- vanadium(V) oxide
- nickel
- platinum
Show answer
A: iron
Haber (NH₃) uses finely divided iron; Contact process uses V₂O₅.
- Contact process
- Hydrogenation of oils
- Fermentation
- Haber process
Show answer
D: Haber process
Iron catalyses N₂ + 3H₂ ⇌ 2NH₃.
- Haber process
- fermentation
- hydrogenation of oils
- Contact process
Show answer
C: hydrogenation of oils
Making margarine.
- oxygen
- sulphur dioxide and nitrogen oxides
- carbon monoxide
- methane
Show answer
B: sulphur dioxide and nitrogen oxides
They form acids in rain water.
- carbon dioxide
- oxygen
- nitrogen
- helium
Show answer
A: carbon dioxide
It traps infrared radiation.
Key words
- Radioactivity
- The spontaneous emission of radiation from unstable atomic nuclei.
- Isotopes
- Atoms of the same element with different numbers of neutrons.
- Radioisotope
- A radioactive isotope.
- Alpha particle
- A helium nucleus, ⁴₂He, with two protons and two neutrons.
- Beta particle
- A fast-moving electron emitted from a nucleus when a neutron changes into a proton.
- Gamma ray
- High-energy electromagnetic radiation emitted from a nucleus.
- Half-life
- The time taken for half the radioactive atoms in a sample to decay.
- Nuclear fission
- The splitting of a heavy nucleus into two lighter nuclei with release of energy and neutrons.
- Nuclear fusion
- The joining of light nuclei to form a heavier nucleus with release of energy.
- Chain reaction
- A self-sustaining fission process in which neutrons from one fission cause further fissions.
- Pollutant
- A substance that harms the environment or living things.
- Acid rain
- Rain made acidic by dissolved oxides of sulfur and nitrogen.
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