Metal extraction

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Lesson notes

Ores and the Reactivity Series

Many metals are found in the Earth in rocks called ores.
To obtain metals, we must extract them from their ores.
The reactivity series lists metals from most reactive to least reactive.
Very reactive metals: potassium, sodium. Unreactive metals: gold, silver.
The method of extraction depends on the metal's position in the reactivity series.

Iron is extracted from iron ore in a blast furnace. Removing oxygen from the iron oxide produces iron.

Extraction Using Carbon (Displacement)

If a metal is less reactive than carbon, it can be extracted by heating its ore with carbon.
This is a displacement reaction: carbon displaces the metal from its oxide.
Example: iron oxide + carbon → iron + carbon dioxide.
Example: copper oxide + carbon → copper + carbon dioxide.
The reaction is a reduction because the metal oxide loses oxygen.

Diagram showing the raw materials, zones and reactions of the blast furnace, and the tapping off of slag and molten iron.

Extraction Using Electrolysis

If a metal is more reactive than carbon, carbon cannot displace it.
Such metals must be extracted using electrolysis.
Electrolysis uses electricity to break down the ore into the metal and other elements.
Examples: aluminium, magnesium are extracted by electrolysis.

Diagram showing the electrolysis cell for extracting aluminium: graphite electrodes, purified aluminium oxide dissolved in molten cryolite, and molten aluminium tapped off.

Unreactive Metals Found Pure

Very unreactive metals like gold and silver are found as pure metals in nature.
They do not need chemical extraction from ores.

Summary of Extraction Methods

Metals below carbon in reactivity series: extracted with carbon (displacement).
Metals above carbon: extracted by electrolysis.
Gold and silver: found pure, no extraction needed.

Atomic structure of iron (Fe), a metal commonly extracted using carbon.

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Practice questions

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1.Which of the following metals can be found as a pure metal in the Earth?
Easy
- AGold
- BIron
- CZinc
- DAluminium
2.What is the name for rocks that contain metals?
Easy
- AOres
- BMinerals
- CMetals
- DCompounds
3.Which method is used to extract a metal that is less reactive than carbon?
Easy
- ADisplacement reaction with carbon
- BElectrolysis
- CFractional distillation
- DFiltration
4.Complete the word equation: carbon + iron oxide → ?
Medium
- Airon + carbon dioxide
- Biron + carbon monoxide
- Ciron oxide + carbon
- Dcarbon dioxide + iron oxide
5.Which metal cannot be extracted from its ore by heating with carbon?
Medium
- AAluminium
- BIron
- CCopper
- DZinc
6.Why is electrolysis used to extract aluminium instead of carbon?
Medium
- AAluminium is more reactive than carbon
- BAluminium is less reactive than carbon
- CCarbon is too expensive
- DAluminium oxide does not react with carbon
7.The reaction: magnesium oxide + carbon → magnesium + carbon dioxide is not possible. Why?
Hard
- AMagnesium is more reactive than carbon
- BCarbon is more reactive than magnesium
- CMagnesium oxide is very stable
- DCarbon dioxide is not formed
8.True or false: Carbon can displace calcium from calcium oxide.
Easy
- AFalse
- BTrue
- CIt depends on temperature
- DOnly if calcium is molten

More questions

9.In the blast furnace, what is the purpose of carbon (coke)?
Medium
- ATo remove oxygen from the iron oxide
- BTo add carbon to the iron
- CTo melt the iron ore
- DTo increase the temperature
10.Which of the following lists metals in order of decreasing reactivity?
Medium
- APotassium, zinc, gold
- BGold, zinc, potassium
- CZinc, potassium, gold
- DPotassium, gold, zinc
11.A metal X is found as a pure metal in the Earth. What can be concluded about X?
Hard
- AX is very unreactive
- BX is very reactive
- CX is a transition metal
- DX is expensive
12.Which of the following metals would require electrolysis for extraction?
Hard
- AMagnesium
- BIron
- CCopper
- DSilver
13.A student is given an unknown metal oxide. When heated with carbon, no reaction occurs. What can be concluded about the unknown metal?
Medium
- AIt is less reactive than carbon.
- BIt is more reactive than carbon.
- CIt is found as a pure metal in the Earth.
- DIt is a transition metal.
14.In a blast furnace, 160 tonnes of iron(III) oxide (Fe₂O₃) reacts with carbon. What is the maximum mass of iron that can be produced? (Ar: Fe = 56, O = 16, C = 12)
Hard
- A56 tonnes
- B112 tonnes
- C160 tonnes
- D224 tonnes
15.The table shows the reactivity of four metals with oxygen. Which metal is most likely to be extracted by heating its oxide with carbon?
Medium
- AMetal A: reacts violently with oxygen
- BMetal B: reacts slowly with oxygen
- CMetal C: reacts very slowly with oxygen
- DMetal D: does not react with oxygen
16.Which of the following is the correct word equation for the extraction of zinc from zinc oxide using carbon?
Easy
- Acarbon + zinc oxide → zinc + carbon monoxide
- Bcarbon + zinc oxide → zinc + carbon dioxide
- Ccarbon + zinc oxide → zinc oxide + carbon
- Dcarbon + zinc oxide → zinc carbonate
17.A student heats 10 g of copper(II) oxide with excess carbon and obtains 6.4 g of copper. What is the percentage yield? (Ar: Cu = 64, O = 16)
Hard
- A50%
- B80%
- C100%
- D64%
18.The graph shows the mass of metal produced when 100 g of each metal oxide is reacted with excess carbon. Which metal oxide is most likely to be that of a metal more reactive than carbon?
Medium
- AMetal oxide A: 78 g metal produced
- BMetal oxide B: 55 g metal produced
- CMetal oxide C: 0 g metal produced
- DMetal oxide D: 63 g metal produced
19.Which statement about the extraction of aluminium is correct?
Easy
- AAluminium is extracted by heating its ore with carbon.
- BAluminium is extracted by electrolysis because it is more reactive than carbon.
- CAluminium is found as a pure metal in the Earth.
- DAluminium is extracted by reduction with hydrogen.
20.A company extracts a metal from its ore using carbon. The metal is then used to make a strong alloy. Which metal is most likely being extracted?
Medium
- APotassium
- BMagnesium
- CIron
- DGold
21.In an experiment, 50 g of zinc oxide is mixed with carbon and heated. The mass of zinc produced is 32 g. What is the mass of carbon dioxide produced? (Ar: Zn = 65, O = 16, C = 12)
Hard
- A18 g
- B22 g
- C44 g
- D11 g
22.A student investigates the extraction of copper. They heat 5 g of copper(II) oxide with carbon and obtain 3.2 g of copper. What is the percentage yield? (Ar: Cu = 64, O = 16)
Medium
- A50%
- B80%
- C64%
- D100%
23.Which of the following metals is least likely to be extracted by heating its ore with carbon?
Easy
- AZinc
- BIron
- CCopper
- DPotassium
24.The diagram shows the reactivity series of four metals. Metal W is the most reactive, X is next, Y is next, and Z is the least reactive. Carbon is between X and Y. Which metal(s) can be extracted by heating with carbon?
Hard
- AW only
- BX and W
- CY and Z
- DZ only
25.In an experiment to extract copper from copper(II) oxide, a student heats 5.0 g of copper(II) oxide with excess carbon. After the reaction, 3.2 g of copper is obtained. What is the percentage yield? (Ar: Cu = 63.5, O = 16.0)
Medium
- A80%
- B64%
- C50%
- D100%
26.A student investigates the extraction of iron from iron(III) oxide using carbon. They set up an experiment with 10.0 g of Fe₂O₃ and excess carbon. After heating, the mass of the solid residue is 7.6 g. What is the mass of iron produced? (Ar: Fe = 56, O = 16)
Hard
- A7.0 g
- B7.6 g
- C6.0 g
- D5.6 g
27.A student places samples of four metal oxides in separate test tubes with carbon powder and heats them strongly. Which metal oxide is least likely to show a reaction?
Medium
- ACalcium oxide
- BZinc oxide
- CIron(III) oxide
- DCopper(II) oxide
28.In an experiment, 8.0 g of copper(II) oxide is heated with excess carbon. The mass of copper produced is 5.6 g. What is the percentage yield? (Ar: Cu = 63.5, O = 16.0)
Hard
- A87.5%
- B70.0%
- C80.0%
- D90.0%
29.Which of the following metals would require electrolysis to extract it from its ore?
Easy
- AAluminium
- BIron
- CCopper
- DZinc
30.A student tests the reactivity of four metals by heating them with oxygen. The table shows the results. Which metal is most likely to be extracted by heating its oxide with carbon?
Medium
- AMetal T: burns brightly with a white flame
- BMetal U: burns slowly with a yellow flame
- CMetal V: does not burn, forms a black coating
- DMetal W: no reaction
31.In the blast furnace extraction of iron, what is the purpose of carbon (coke)?
Medium
- ATo provide heat by burning and to act as a reducing agent
- BTo increase the temperature only
- CTo remove impurities as slag
- DTo supply oxygen for the reaction
32.A student performs an extraction of zinc from zinc oxide using carbon. They heat 20.0 g of zinc oxide with excess carbon and obtain 13.0 g of zinc. What is the mass of carbon dioxide produced? (Ar: Zn = 65, O = 16, C = 12)
Hard
- A7.0 g
- B4.4 g
- C8.8 g
- D5.5 g
33.A student heats 12.0 g of a metal oxide with excess carbon and obtains 8.4 g of the metal. The molar mass of the metal is 56 g/mol and the oxide contains 30% oxygen by mass. What is the formula of the metal oxide?
Hard
- AMO
- BM₂O₃
- CMO₂
- DM₂O
34.Which of the following statements about the extraction of aluminium is correct?
Medium
- AAluminium is extracted by heating its oxide with carbon because it is less reactive than carbon.
- BAluminium is extracted by electrolysis because it is more reactive than carbon.
- CAluminium is found as a pure metal in the Earth and does not need extraction.
- DAluminium is extracted by heating its oxide with hydrogen.
35.A student adds carbon to three metal oxides and heats them. The results are shown. Which oxide reacted?
Medium
- AOxide of metal A: no change
- BOxide of metal B: black solid turns brown
- COxide of metal C: white solid remains white
- DOxide of metal D: yellow solid turns green
36.Which of the following metals can be found as a pure metal in the Earth's crust?
Easy
- AGold
- BIron
- CZinc
- DAluminium
37.An unknown metal oxide is heated with carbon. A reaction occurs, producing the pure metal and carbon dioxide. What can be concluded about the unknown metal?
Medium
- AIt is less reactive than carbon.
- BIt is more reactive than carbon.
- CIt is unreactive like gold.
- DIt is the same reactivity as carbon.
38.In the extraction of iron, iron(III) oxide (Fe₂O₃) is reduced by carbon. Which of the following best describes the role of carbon?
Medium
- ACarbon acts as a reducing agent, removing oxygen from iron oxide.
- BCarbon acts as an oxidising agent, adding oxygen to iron.
- CCarbon provides energy by burning, but does not react with iron oxide.
- DCarbon melts the iron ore so that iron can be separated.
39.A student heats 8.0 g of copper(II) oxide (CuO) with excess carbon and obtains 5.6 g of copper. What is the percentage yield? (Ar: Cu = 63.5, O = 16.0)
Hard
- A87.5%
- B70.0%
- C56.0%
- D44.8%
40.In an experiment, 50 g of zinc oxide (ZnO) is mixed with carbon and heated. The mass of zinc produced is 32 g. What is the mass of carbon dioxide produced? (Ar: Zn = 65, O = 16, C = 12)
Medium
- A18 g
- B22 g
- C44 g
- D11 g

Revision notes

## Metal Extraction Revision Notes ### Key Concepts - **Ores**: Rocks containing metals. Most metals are found in ores and must be extracted. - **Reactivity Series**: Lists metals from most reactive (e.g., potassium) to least reactive (e.g., gold). ### Extraction Methods 1. **Metals less reactive than carbon**: Extracted by **displacement reaction** with carbon (reduction). - Iron: iron oxide + carbon → iron + carbon dioxide - Copper: copper oxide + carbon → copper + carbon dioxide - Zinc: zinc oxide + carbon → zinc + carbon dioxide 2. **Metals more reactive than carbon**: Cannot be displaced by carbon; require **electrolysis**. 3. **Very unreactive metals (e.g., gold, silver)**: Found as pure metals; no extraction needed. ### Important Points - Carbon displaces metals below it in the reactivity series. - Reduction: removal of oxygen from a metal oxide. - Example: iron oxide + carbon → iron + carbon dioxide (carbon removes oxygen). - Electrolysis is used for reactive metals like aluminium and magnesium. ### Common Mistakes - Carbon cannot displace metals above it (e.g., magnesium, aluminium). - Gold and silver are found pure, not extracted by chemical reactions.

Ore: A rock containing a metal compound from which the metal can be extracted.
Reactivity series: A list of metals ordered from most reactive to least reactive.
Displacement reaction: A reaction where a more reactive element takes the place of a less reactive element in a compound.
Reduction: A reaction that removes oxygen from a metal oxide, separating the metal.
Electrolysis: A method using electricity to extract a metal from its ore, used for metals more reactive than carbon.

Flashcards

What is an ore?

A rock that contains metals, from which metals can be extracted.

What is the reactivity series?

A list that shows metals from most reactive to least reactive.

Which metals are very reactive?

Potassium and sodium are very reactive.

Which metals are not very reactive?

Gold and silver are not very reactive.

How can a metal less reactive than carbon be extracted?

By a displacement reaction using carbon.

What is a reduction reaction?

A reaction that separates a metal from a metal oxide.

Write the word equation for extracting iron from iron oxide using carbon.

iron oxide + carbon → iron + carbon dioxide

Write the word equation for extracting copper from copper oxide using carbon.

copper oxide + carbon → copper + carbon dioxide

How is a metal more reactive than carbon extracted?

By electrolysis.

Why don't gold and silver need to be extracted by chemical reactions?

Because they are very unreactive and can be found as pure metals.

True or false: Gold can be found as a pure metal.

True.

True or false: Zinc is more reactive than carbon.

False.

True or false: Iron can be extracted from its ore by heating with carbon.

True.

True or false: Aluminium can be extracted from its ore by heating with carbon.

False.

True or false: Magnesium can be extracted from its ore by electrolysis.

True.

True or false: Carbon would not displace calcium from calcium oxide.

True.

Complete: carbon + iron oxide → _____ + _____

iron + carbon dioxide

Complete: carbon + zinc oxide → _____ + _____

zinc + carbon dioxide

Why is the reaction magnesium oxide + carbon → magnesium + carbon dioxide not possible?

Because magnesium is more reactive than carbon, so carbon cannot displace magnesium.

Explain why carbon is used to extract iron and copper but not aluminium.

Carbon is less reactive than aluminium, so it cannot displace aluminium from its ore. Aluminium requires electrolysis.

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