What is the main use of the ammonia made by the Haber process?

Making nitrogen-containing fertilisers.

Explain how making ammonia on a large scale increases food production.

It supplies cheap nitrogen fertiliser, which raises the crop yield obtained from the same area of land.

What happens to the nitrogen content of soil that is cropped year after year without fertiliser?

It falls, because every harvest removes nitrogen compounds that are not replaced.

Before the Haber process, where did farmers get nitrogen compounds for their fields?

From manure and from mined natural deposits of nitrates, both of which were limited in supply.

OCR GCSE Chemistry A J248

Chemical Reactions

Topic overview Writing formulae of elements and compounds Balanced equations, and deducing formulae from ions Ionic equations, and state symbols The mole and the Avogadro constant Conservation of mass, and changes of mass in open systems Stoichiometry, and calculating reacting masses Exothermic and endothermic reactions, and reaction profiles Activation energy, and bond energy calculations Oxidation and reduction, by oxygen and by electrons Acids, alkalis and neutralisation The ionic equation for neutralisation, and reactions of acids Dilute and concentrated, weak and strong The pH scale, and hydrogen ion concentration pH as a factor of ten, and measuring pH Products at the electrodes, and molten ionic compounds Electrolysis of aqueous solutions Inert and non-inert electrodes

Elements, Compounds and Mixtures

Topic overview Purity, and melting point data Relative formula mass and empirical formulae Formulations, and separating mixtures Paper and thin layer chromatography Interpreting chromatograms and Rf values Choosing a purification method Metals and non-metals in the Periodic Table Electron arrangement and position in the Periodic Table Ionic, covalent and metallic bonding compared Dot and cross diagrams, and the limits of models Reactions, electron arrangement and Mendeleev's table Carbon's four bonds, and the variety of organic compounds Diamond, graphite, fullerenes and graphene Bond strength, intermolecular forces and predicting state Bulk properties of ionic, molecular and giant structures Nanoparticles: size and surface area to volume Uses and risks of nanoparticulate materials

Global Challenges

Topic overview Extracting metals by reduction and by electrolysis Biological methods of metal extraction Rate against yield in industry, and reaction conditions The Haber process and fertiliser production Nitrogen, phosphorus and potassium in agriculture Life cycle assessment Recycling, and the decisions behind it Alloys, and the corrosion of metals Comparing glass, ceramics, polymers, composites and metals Functional groups and homologous series Predicting the products of organic reactions Addition polymerisation Condensation polymerisation, and making a polymer DNA and other natural polymers Fractional distillation of crude oil The fractions, and crude oil as a feedstock Dependence on hydrocarbons, and cracking Chemical cells and fuel cells The Earth's early atmosphere, and how oxygen developed The greenhouse effect, and evidence for climate change Effects of carbon dioxide and methane, and air pollutants Producing potable water

Monitoring and Controlling Chemical Reactions

Topic overview Concentration in mol/dm³, and titration Titration calculations, and the mass of a solute Molar gas volume and the volumes of gases Theoretical mass and percentage yield Atom economy, and choosing a reaction pathway Measuring the rate of a reaction, and rate graphs Factors affecting rate, and collision theory Surface area and rate Catalysts and how they work Reversible reactions and dynamic equilibrium Changing the conditions of an equilibrium Activation energy, and enzymes as catalysts

Particles

Topic overview The particle model and changes of state Limitations of the particle model How the atomic model changed, and the structure of the atom The size of atoms, and the subatomic particles Calculating protons, neutrons and electrons

Predicting and Identifying Reactions

Topic overview Groups 1, 7 and 0, and why they behave as they do Transition metals Predicting reactivity from the Periodic Table Reactivity of metals with water and acids Tests for oxygen, hydrogen, carbon dioxide and chlorine Tests for aqueous cations and anions Flame tests, and identifying metal ions Identifying a species from test results Instrumental methods of analysis

Global Challenges

The Haber process and fertiliser production

2 things to know
Paper 4

Overview

What the ammonia from the Haber process is mainly used for, why crops need nitrogen compounds and how cheap fertiliser raises food production, where farmers got nitrogen before, the algal growth that fertiliser run-off causes, preparing ammonium sulfate by titration and crystallisation in the laboratory, and how industrial production differs in scale, acid concentration, automation and continuous running.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why do crops need nitrogen compounds from fertiliser rather than taking nitrogen from the air?

Process

Which two substances are combined in the Haber process, and what is produced?

Questions from this subtopic

Each one with the model answer underneath.

1
What is the main use of the ammonia made by the Haber process?
Model answer
Making nitrogen-containing fertilisers.
2
Why do crops need nitrogen compounds from fertiliser rather than taking nitrogen from the air?
Model answer
Plants cannot use nitrogen gas directly, so they take up soluble nitrogen compounds through their roots.
3
Explain how making ammonia on a large scale increases food production.
Model answer
It supplies cheap nitrogen fertiliser, which raises the crop yield obtained from the same area of land.
4
What happens to the nitrogen content of soil that is cropped year after year without fertiliser?
Model answer
It falls, because every harvest removes nitrogen compounds that are not replaced.
5
Which two substances are combined in the Haber process, and what is produced?
Model answer
Nitrogen and hydrogen combine to produce ammonia.
6
Before the Haber process, where did farmers get nitrogen compounds for their fields?
Model answer
From manure and from mined natural deposits of nitrates, both of which were limited in supply.

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Chemical Reactions

Elements, Compounds and Mixtures

Global Challenges

Monitoring and Controlling Chemical Reactions

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