Making Useful Chemicals

How can metals be arranged in order of their reactivity?

Metals like potassium, sodium, lithium, calcium, magnesium, zinc, iron, and copper can be arranged based on their reactions with water and dilute acids.

Are non-metals included in the reactivity series?

Yes, non-metals such as hydrogen and carbon are often included in the reactivity series.

What happens when a more reactive metal displaces a less reactive metal from a compound?

The more reactive metal can displace the less reactive metal from the compound.

Why is gold second to last in the reactivity series?

Gold is very unreactive and is found in the Earth as the metal itself.

Where are most metals found?

Most metals are found as compounds that require chemical reactions to extract the metal.

How can metals less reactive than carbon be extracted?

Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.

What does reduction involve?

Reduction involves the loss of oxygen.

Why are metals like aluminium extracted by electrolysis?

Metals more reactive than carbon, like aluminium, are extracted by electrolysis because they are too reactive to be extracted by reduction with carbon.

How is aluminium manufactured by electrolysis?

Aluminium is manufactured by electrolysis of a molten mixture of aluminium oxide and cryolite, using carbon as the positive electrode (anode).

What does the extraction process for metals like aluminium involve?

The extraction process requires large amounts of energy to melt the compounds and to produce the electrical current.

What are the alternative biological methods for metal extraction?

Phytoextraction involves plants absorbing metal compounds, while bacterial extraction uses bacteria to absorb metal compounds and produce leachates.

What is the trade-off between the rate of production and the position of equilibrium in industrial processes?

A compromise is needed between a large yield (position of equilibrium) and a fast rate of reaction (rate of a desired product), often using moderate temperature/pressure to balance both.

What happens at lower temperatures and pressures in reactions?

A lower temperature or pressure may favor the position of equilibrium but result in a slower rate of reaction and lower yield of product.

Why are high temperatures and pressures used in industrial processes?

High temperatures or pressures are used if they favor the equilibrium, but a limit is set to save money and prevent danger.

How do reaction conditions affect the rate?

In general, higher temperatures increase the rate of reaction.

How are commercially used conditions for an industrial process related to the availability and cost of raw materials?

High temperatures and pressures require large energy supplies, and catalysts are often used in almost all industrial processes to improve efficiency.

Why is the Haber process important for agricultural production?

The Haber process is used to manufacture ammonia, which is essential for producing nitrogen-based fertilizers.

What are the raw materials for the Haber process?

The raw materials are nitrogen (from air) and hydrogen (from natural gas or steam).

How does the Haber process work?

Nitrogen and hydrogen react over an iron catalyst at 450°C and 200 atmospheres pressure to form ammonia. The reaction is reversible, and the ammonia is removed by cooling and recycling the remaining nitrogen and hydrogen.

How does the industrial production of fertilisers differ from laboratory synthesis?

In industry, large-scale production using natural gas, air, water, and sulfuric acid occurs, while in labs, small-scale synthesis with ammonia solution and dilute sulfuric acid is used.

What is the importance of nitrogen, phosphorus, and potassium compounds in agriculture?

These compounds are used as fertilizers to improve agricultural productivity by providing soluble elements for plants to absorb.

What is the industrial process for producing fertilisers?

NPK fertilisers are made using ammonia, which can be combined with nitric acid to make ammonium nitrate or sulfuric acid to make ammonium sulfate.

How is phosphate rock treated to make fertilisers?

Phosphate rock is treated with nitric acid or sulfuric acid to produce soluble salts that can be used as fertilisers.

What are the basic principles of carrying out a life-cycle assessment (LCA)?

LCA evaluates the environmental impact of a product during raw material extraction, manufacturing, use, and disposal, including transport and resource use at each stage.

Why is the allocation of pollutant effects in LCA not straightforward?

Allocating numerical values to pollutant effects requires value judgements, making LCA a subjective process.

What does recycling for a different use involve?

Recycling reduces the use of limited resources, energy consumption, and waste, and some materials, like glass and metals, can be reused or recycled for other purposes.

How are metals recycled?

Metals can be recycled by melting and recasting or reforming into different products.

What factors affect decisions on recycling?

Advantages include preserving materials and saving energy, while disadvantages include the energy cost of collection and transportation, and the need for sorting materials.

What are some important alloys and their uses?

Brass (copper and zinc) for hinges, bronze (copper and tin) for castings, duralumin (aluminium, copper) for aircraft, and various steels for different applications like low-carbon for shaping and stainless for corrosion resistance.

What is corrosion, and what conditions cause it?

Corrosion is the destruction of materials by chemical reactions, and rusting requires both oxygen and water.

How can corrosion be mitigated by sacrificial protection?

Sacrificial protection uses a more reactive metal, like zinc, to prevent rusting by corroding first, protecting the metal beneath.

What are the physical properties of glass, clay ceramics, polymers, and metals?

Glass is transparent and brittle, clay ceramics are hard and brittle, polymers can be tough or ductile, and metals are shiny, hard, and good conductors of heat and electricity.