How does the oxidation number of Carbon change in this reaction C(s) + O2(g) → CO2(g) ?

To determine the change in the oxidation number of carbon in the reaction \( C(s) + O_2(g) \rightarrow CO_2(g) \), we first need to assign oxidation states to the elements in the reactants and products.

1. In its elemental form, carbon (C) in \( C(s) \) has an oxidation number of 0.
2. In the molecular oxygen \( O_2(g) \), oxygen also has an oxidation number of 0 since it is in its elemental form.

Now, in the product \( CO_2(g) \):

• Oxygen typically has an oxidation number of -2. Since there are two oxygen atoms in carbon dioxide, the total contribution from the oxygen is \( 2 \times (-2) = -4 \).
• To find the oxidation number of carbon in \( CO_2 \), we set up the equation considering that the sum of oxidation numbers in a neutral compound must equal zero: \[ \text{Oxidation number of C} + \text{Sum of oxidation numbers of O} = 0 \] \[ x + (-4) = 0 \] Solving for \( x \), we find: \[ x = +4 \]

So, in \( CO_2(g) \), the oxidation number of carbon is +4.

Overall, carbon changes from an oxidation number of 0 in its elemental form (C) to +4 in carbon dioxide (CO2).

Thus, the change in the oxidation number of carbon during the reaction is: \[ \text{From } 0 \text{ to } +4. \]