Extracting Metals Flashcards
All 9 cards in this deck
What is an ore?
A rock containing enough of a metal compound to make extracting the metal worthwhile.
Why are gold and silver found in the Earth's crust as uncombined (native) elements?
They are very unreactive, so they do not readily react with other elements to form compounds.
In terms of oxygen, what are oxidation and reduction?
Oxidation is the gain of oxygen; reduction is the loss of oxygen.
Why is extracting a metal from its ore described as reduction?
Oxygen (or electrons are gained by the metal ions) is removed from the ore to leave the metal.
How do you decide whether a metal is extracted by heating with carbon or by electrolysis?
e.g. calcium
- Find the metal's position relative to carbon in the reactivity series: calcium is above carbon.
- Above carbon → electrolysis; below carbon → heat with carbon.
- So calcium is extracted by electrolysis.
Why can't aluminium be extracted by heating its oxide with carbon?
Aluminium is more reactive than carbon, so carbon cannot remove the oxygen (cannot displace aluminium).
Why is extraction by electrolysis more expensive than reduction with carbon?
Electrolysis uses large amounts of electrical energy (and the ore must be melted or dissolved).
Write the word equation for the extraction of iron by heating iron oxide with carbon, and say what is reduced.
iron oxide + carbon → iron + carbon dioxide; the iron oxide is reduced (carbon is oxidised).
How is a metal's resistance to oxidation related to its position in the reactivity series?
The lower a metal is in the reactivity series, the more resistant it is to oxidation/corrosion.