In this combustion reaction, the oxidation numbers of carbon and hydrogen change.
In acetylene (C2H2), each carbon atom has an oxidation number of +1 and each hydrogen atom has an oxidation number of -1. In the products (CO2 and H2O), carbon in CO2 has an oxidation number of +4 and hydrogen in H2O has an oxidation number of +1.
The oxidation numbers of carbon and hydrogen increase during the reaction, indicating that they are oxidized. This means that carbon and hydrogen lose electrons during the reaction.
Therefore, in the reaction:
- Carbon is oxidized from +1 to +4
- Hydrogen is oxidized from -1 to +1
Since carbon and hydrogen are oxidized, the oxygen in the reactant O2 is effectively reduced. Oxygen in O2 has an oxidation number of 0 and in the product, it has an oxidation number of -2.
During the reaction, electrons are transferred from carbon and hydrogen to oxygen. This transfer of electrons demonstrates that the reaction is a redox reaction.
The reaction for the combustion of acetylene is shown. Explain why this reaction is a redox reaction by identifying the oxidation numbers that change, what is oxidized, what is reduced, and what happens to the electrons during the reaction.
2C2H2 + 5O2 → 4CO2 + 2H2O
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