CH4 + 2 O2 = CO2 + H2O
Carbon is being oxidized
Oxygen is being reduced
I didn't realize until I read this that I answered your other one (Mg and O2) wrong. I've gone back and changed that. This one looks ok.
C goes from -4 to +4, loss of electrons which is oxidization.
To determine which elements are being oxidized or reduced in a chemical reaction, you can use the concept of oxidation numbers. Oxidation numbers are assigned to atoms in a compound to indicate their electron loss or gain during a chemical reaction.
In the given equation: CH4 + 2 O2 = CO2 + H2O
To find the oxidation number of an atom in a compound:
1. Determine the most electronegative element in the compound. In this case, oxygen (O) is more electronegative than carbon (C).
2. Assign the shared electrons to the more electronegative atom. Hydrogen (H) is bonded to carbon, so it will be assigned to carbon.
3. Determine the oxidation number of the remaining atoms based on the electronegativity difference or known common oxidation numbers.
Let's determine the oxidation numbers for carbon and oxygen:
In methane (CH4), hydrogen has an oxidation number of +1 since it usually donates its electron to another atom. The overall charge of methane is 0, so the carbon must have an oxidation number of -4 to balance out the hydrogen atoms.
In carbon dioxide (CO2), oxygen has an oxidation number of -2 since it is more electronegative. The overall charge of carbon dioxide is 0, so the carbon must have an oxidation number of +4 to balance out the oxygen atoms.
In water (H2O), hydrogen has an oxidation number of +1, and since it is bonded to oxygen, oxygen must have an oxidation number of -2 to balance out the hydrogen atoms.
Now, let's look at the changes in oxidation numbers:
In CH4, carbon has an oxidation number of -4. In CO2, the oxidation number of carbon is +4. Hence, the carbon is oxidized since its oxidation number increased from -4 to +4, indicating a loss of electrons.
In O2, oxygen has an oxidation number of 0. In H2O, the oxidation number of oxygen is -2. Hence, oxygen is reduced since its oxidation number decreased from 0 to -2, indicating a gain of electrons.
To summarize:
- In this chemical equation, carbon undergoes oxidation, as its oxidation number increases from -4 to +4.
- Oxygen undergoes reduction, as its oxidation number decreases from 0 to -2.
These changes in oxidation numbers indicate that carbon is being oxidized, and oxygen is being reduced in the given chemical reaction.