How Rocks Provide Metals

Mr Rogers

How do rocks provide metals? LO’s •Know the four stages of extraction of metals. •What a REDOX reaction is.

Homework • Pages 6 – 9 and 11 in workbook. • You’ve already done some of these in yesterdays lesson. • Due in next Tuesday.

How do rocks provide metals? Getting metals from their ores usually involves 4 stages… 1. Mining the ore

2. Concentrating the ore The ore is smashed up into very small pieces, then most of the soil and rock can be removed. Example: Froth Flotation •Crushed ore mixed with water. •Air is bubbled up through the liquid. •Ore particles ‘stick’ to the bubbles, the rock / soil / sand does not. •The ore can be collected in the froth at the top.

3. Reducing the ore Chemically changing the ore from metal compounds (e.g.. metal oxides) to metals.

1.

Purifying the metal

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This removes any remaining impurities.

How we reduce the ore depends on the position in the reactivity series.

We have a good supply of carbon in the form of coke. •Coke is coal that has been baked in an airless oven at about 2000oC. •Coke is pure carbon.

Displacement reactions • A more reactive substance takes the place of (displaces) a less reactive substance. • What would happen if we reacted silver oxide, Ag2O, with carbon? Write a word equation and a balanced chemical equation with state symbols for this reaction.

Would the metal be displaced if these ores were reacted with carbon? • • • •

Iron oxide Sodium oxide Lead oxide Tin oxide

REDOX In REDOX reactions both a REDuction and an OXidisation take place. In our earlier example of silver oxide: • What happened to the silver during the reaction? • What happened to the carbon during the reaction?

Next time… • What if the metal is above carbon in the reactivity series???

True or false? Once mined, the ore will still be mixed with rock and soil.

True or false? The 4 stages of extraction are mining, concentrating, recycling and purifying.

True or false? Aluminium is more reactive than zinc.

True or false? The next metal in the reactivity series after aluminium is carbon.

True or false? A displacement reaction is one where a less reactive element is replaced by a more reactive element.

True or false? If coal is baked in an oxygen free oven then cola is produced.

True or false? Coke contains one element; carbon

True or false? Carbon will displace a metal from its ore if the metal is more reactive than carbon.

True or false? If water is reduced hydrogen is produced.

True or false? In redox, the ox stands for oxification.