9 3 extraction of metals

The reactivity series orders metals from most reactive to least reactive.

Metals above carbon in the reactivity series are extracted by electrolysis.

False. The most reactive metals are at the top of the reactivity series.

The position of the metal on the reactivity series determines the extraction method.

Metals that must be extracted by electrolysis are higher up the reactivity series (above carbon) and include aluminum, sodium, potassium, calcium, lithium and magnesium.

False. Iron is extracted by reduction / in the blast furnace.

Metals below carbon in the reactivity series are extracted by heating / reduction with carbon.

False. Metals higher up are less resistant to oxidation than the metals placed lower down which are more resistant to oxidation.

The extraction of metals by heating with carbon is a reduction reaction.

False. Iron is extracted by reduction / in the blast furnace.

The raw materials added to a blast furnace for the extraction of iron are iron ore, coke and limestone.

The main iron ore is haematite.

The balanced symbol equation for the reduction of iron(III) oxide by carbon monoxide is: Fe2O3 (s)  +  3CO (g)  →  2Fe (I)  +  3CO2 (g)

False. In the first stage of the extraction of iron, coke reacts with oxygen to form carbon dioxide.

True. The thermal decomposition of calcium carbonate produces calcium oxide and carbon dioxide.

Limestone is added to a blast furnace to remove impurities in the ore.

The product formed in the blast furnace when carbon reacts with carbon dioxide is carbon monoxide.

Molten slag is calcium silicate formed when calcium oxide reacts with silicon dioxide.

True. The symbol equation for the formation of slag is: CaO (s)  +  SiO2 (s)  →  CaSiO3 (l)

The symbol equation for the reduction of carbon dioxide to carbon monoxide is: CO2 (g)  +  C (s)  →  2CO (g)

The main ore of aluminium is bauxite.

False. Aluminium is extracted using electrolysis.

Aluminium oxide is dissolved in molten cryolite to lower its melting point and reduce the amount of energy required.

The electrodes are made from graphite / carbon.

True. Oxygen is formed at the anode during the electrolysis of aluminium oxide.

The half-equation that occurs at the cathode during the electrolysis of aluminium oxide is: Al3+ +  3e-   →  Al

False. During the electrolysis of aluminium oxide, the oxide ions are oxidised (lose electrons) at the anode.

Reduction is the gain of electrons.

The anode needs to be replaced regularly during the electrolysis of aluminium oxide because the oxygen produced reacts with the carbon electrodes to produce carbon dioxide, causing the anode to wear away.

Electrolysis is expensive as it uses a lot of energy / electricity.

The ionic half-equation that occurs at the anode during the electrolysis of aluminium oxide is: 2O2- →   O2 + 4e-