### ZIMSEC O Level Combined Science Notes:  The reduction process

• Reduction is the opposite of oxidation
• Reduction is the removal of oxygen from a substance/compound
• It can also be the addition of oxygen

The reduction of copper.

• reducing agent removes oxygen or adds hydrogen
• Metals cannot be yielded by heating their oxides
• The metals have to be heated with a reducing agent
• That will remove the oxygen from the oxide to yield the metal
• The metal oxide is reduced into a metal
• The reducing agent that can be used can be any of the following:
• a metal that is higher up in the reactivity series when compared to the metal being extracted
• hydrogen
• or it could be carbon
• All these can act as reducing agent
• For example:
• $\text{copper oxide+hydrogen}\rightarrow\text{copper+water}$
• Hydrogen can be used to remove (displace)  oxygen from a compound
• Carbon can also be used to reduce copper oxide yielding the copper
• The equation can be written as:
• $\text{copper oxide+carbon}\rightarrow\text{copper+carbon dioxide}$
• A metal that is higher up in the reactivity series can be used to reduce a metal that is lower in the reactivity series
• This is because the more reactive has a higher affinity for oxygen when compared to the metal that is lower in the series
• The more reactive metal will thus “take” oxygen from the less reactive metal
• The more reactive metal displaces the less reactive metal
• This leaves the less reactive metal and an oxide of the more reactive metal
• For example:
• $\text{iron oxide+aluminium}\rightarrow\text{iron+aluminium dioxide}$
• Aluminum is higher up in the reactivity series when compared to iron
• The aluminum reduces the iron (III)  oxide to leave iron and aluminum oxide
• A lot of heat is given out in the reaction
• Exothermic reactions give out heat

To access more topics go to the Combined Science Notes page.

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