Extraction of Metals & Reduction Flashcards

All 7 cards in this deck

In what form are unreactive metals such as gold found in the Earth?

As the metal itself (uncombined/native), because they are so unreactive.

Which metals can be extracted from their oxides by reduction with carbon?

Metals less reactive than carbon.
e.g. zinc, iron, copper

What is meant by reduction in a metal extraction reaction?

Loss of oxygen from a substance.

In $2\mathrm{Fe_2O_3} + 3\mathrm{C} \rightarrow 4\mathrm{Fe} + 3\mathrm{CO_2}$, which substance is reduced and which is oxidised?

$\mathrm{Fe_2O_3}$ is reduced because it loses oxygen; carbon is oxidised because it gains oxygen.

How do you decide whether a metal can be extracted by reduction with carbon?

e.g. zinc oxide

1. Find the metal's position in the reactivity series relative to carbon: zinc is below carbon.
2. If it is below carbon, carbon can reduce (displace it from) its oxide: yes for zinc.
3. If it is above carbon, electrolysis must be used instead.

True or false? Most metals are found in the Earth as compounds that need a chemical reaction to extract the metal.

True. Only very unreactive metals such as gold are found as the metal itself.

Why is it a problem to use magnesium rather than carbon to reduce silicon dioxide ($2\mathrm{Mg} + \mathrm{SiO_2} \rightarrow \mathrm{Si} + 2\mathrm{MgO}$)?

Both products are solids, so they are difficult to separate.