MYP Chemistry Topic Extraction Revision Notes

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MYP Chemistry Topic Extraction Revision Notes | RevisionDojo

Why Do We Need to Extract Substances from Natural Resources?

Definition

Extraction

Extraction is the process of obtaining a relatively pure substance from a mixture or compound using physical or chemical methods.

Most metals and many useful substances are not found in a pure, elemental form in nature. Instead, they are usually present as:

Ores – rocks that contain enough of a metal compound to make extraction economical.
Minerals – naturally occurring compounds in the Earth’s crust.
Other compounds mixed with unwanted materials (called gangue).

To use these materials in manufacturing, construction, transport, electronics and medicine, we must first extract and purify them.

Example

Iron:
- Found mainly as iron(III) oxide, Fe₂O₃, in ores such as hematite.
- Must be extracted and purified to make iron and steel for buildings, cars, bridges, etc.
Aluminium:
- Found as aluminium oxide, Al₂O₃, in bauxite ore.
- Pure aluminium metal is not found naturally because it is very reactive and tends to form stable oxides.

Hint

Key idea: Extraction turns natural resources (ores, minerals, mixtures) into useful materials we rely on every day.

How Do Properties and Reactivity Influence Extraction Methods?

The method used to extract a substance depends on:

Its chemical reactivity.
Its position in the reactivity series.
Its bonding (how strongly it is combined with other elements).
Whether it is found as an element or in compounds.

Physical Separation

Some substances can be obtained using physical methods when they:
1. Are already in their elemental (native) form, or
2. Are mixed, but not chemically bonded, with other materials.
Methods include:
1. Filtration
2. Distillation
3. Magnetic separation
4. Panning or sluicing (for dense metals like gold)

Example

Gold

Gold is very unreactive, so it often occurs as native metal ($Au$) rather than in compounds.
It can be separated from sand and gravel by panning, using water to wash away lighter materials.

Chemical Reduction (Using Carbon or Other Reducing Agents)

Many metals are found as metal oxides and must be chemically reduced to obtain the metal.
Metals that are less reactive than carbon can usually be extracted by reducing their oxides with carbon (or carbon monoxide): $$\text{Metal oxide} + \text{carbon (or CO)} \to \text{Metal} + \text{Carbon dioxide}$$

Example

Extraction of Iron (Blast Furnace)

Iron(III) oxide is reduced by carbon monoxide: $$\mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~s})+3 \mathrm{CO}(\mathrm{~g}) \rightarrow 2 \mathrm{Fe}(\mathrm{l})+3 \mathrm{CO}_2(\mathrm{~g})$$
- Iron(III) oxide is reduced to iron.
- Carbon monoxide is oxidised to carbon dioxide.
This works because iron is below carbon in the reactivity series.

Electrolysis (For Very Reactive Metals)

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MYP Chemistry Extraction Notes

Why Do We Need to Extract Substances from Natural Resources?

How Do Properties and Reactivity Influence Extraction Methods?

Physical Separation

Chemical Reduction (Using Carbon or Other Reducing Agents)

Electrolysis (For Very Reactive Metals)

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Why Do We Need to Extract Substances from Natural Resources?

How Do Properties and Reactivity Influence Extraction Methods?

Physical Separation

Chemical Reduction (Using Carbon or Other Reducing Agents)

Electrolysis (For Very Reactive Metals)

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Periodic table5 subtopics

Matter5 subtopics

Types of chemical reaction18 subtopics

International Union of Pure and Applied Chemistry (IUPAC)4 subtopics

Pure and impure substances2 subtopics

The atmosphere2 subtopics

Bonding4 subtopics

MYP Chemistry Extraction Notes

Periodic table5 subtopics

Matter5 subtopics

Types of chemical reaction18 subtopics

International Union of Pure and Applied Chemistry (IUPAC)4 subtopics

Pure and impure substances2 subtopics

The atmosphere2 subtopics

Bonding4 subtopics

Why Do We Need to Extract Substances from Natural Resources?

How Do Properties and Reactivity Influence Extraction Methods?

Physical Separation

Chemical Reduction (Using Carbon or Other Reducing Agents)

Electrolysis (For Very Reactive Metals)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Why Do We Need to Extract Substances from Natural Resources?

How Do Properties and Reactivity Influence Extraction Methods?

Physical Separation

Chemical Reduction (Using Carbon or Other Reducing Agents)

Electrolysis (For Very Reactive Metals)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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