lesson
Updated 6 days ago · 3 views
Every gleaming steel bridge and skyscraper began as red, crumbly iron ore trapped inside solid rock. How do chemical plants strip away the oxygen locked inside that rock to produce pure, shiny metal?
The answer lies in one of the most fundamental partner-processes in chemistry: trading oxygen atoms back and forth.
Oxygen Gain and Loss
In the late 1770s, French chemist Antoine Lavoisier discovered that substances gain mass when they burn because they combine with a specific gas in the air, which he named oxygen.
Oxidation is the gain of oxygen by a substance, while reduction is the loss of oxygen from a substance.
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Because oxygen cannot simply appear or vanish, oxidation and reduction always take place simultaneously. Reactions where these paired processes occur are called redox reactions.
If one chemical species is oxidised (gains oxygen), another chemical species must be reduced (loses oxygen). What happens when a substance burns rapidly in air?
Combustion Reactions as Oxidation
In combustion reactions, fuels or metals burn in air or oxygen, and the reacting elements gain oxygen to form oxides.
When magnesium burns in air, it reacts with oxygen: 2Mg (s)+O2 (g)→2MgO (s) Magnesium gains oxygen to form magnesium oxide, meaning magnesium is oxidised.
Similarly, in the combustion of methane gas: CH4 (g)+2O2 (g)→CO2 (g)+2H2O (g) Carbon gains oxygen to form carbon dioxide, showing that methane's carbon is oxidised.
📊Interactive diagram