Metals and Redox

Question 1

what is oxidation?

Answer 1

the gain of oxygen (or the reaction with)

Question 2

what is reduction?

Answer 2

the loss of oxygen

Question 3

what is the oxidising agent in an oxidation reaction?

Answer 3

the substance that oxidises the metal and is reduced

Question 4

what is the reducing agent in a reduction reaction?

Answer 4

the substance that reduces the metal and is oxidised

Question 5

what is a redox reaction?

Answer 5

reduction and oxidation in the same reaction

Question 6

what are pure metals?

Answer 6

metals that are unreactive don’t tend to form compounds with other elements - unreactive metals such as gold are found uncombined

Question 7

what are metal ores?

Answer 7

• most metals do react with other elements to form compounds, which can be found naturally in the Earth’s crust
• if a compound contains enough of the metal to make it worthwhile extracting, the compound is called a metal ore
• there are limited amounts of metal ores - they are finite resources

Question 8

the more reactive a metal is…

Answer 8

the harder it is to extract it from a compound

Question 9

what common metals form metal oxide ores?

Answer 9

metals like iron and aluminium - these can be separated from its oxide by a reduction reaction

Question 10

what happens during a reduction reaction?

Answer 10

carbon is used as a reducing agent to separate the oxygen from its metal

2Fe2O3 + 3C -> 4Fe + 3CO2

iron oxide + carbon -> iron + carbon dioxide

Question 11

how does carbon extract metals during a reduction reaction?

Answer 11

by heating the ore with carbon monoxide

Question 12

why can only metals that are less reactive than carbon be extracted in a reduction reaction with carbon?

Answer 12

because more reactive elements form compounds more readily - carbon can only take oxygen away from metals which are less reactive than carbon itself

Question 13

what do very reactive metals form?

Answer 13

very stable ores

Question 14

what has to be used to extract metals that are more reactive than carbon?

Answer 14

electrolysis which uses electricity to separate the metal from the other elements in the compound