Question

Determine for each of the following if it is an oxidation-reduction reaction.

a. CaO (s) + CO2 (g) à CaCO3 (s)

Answer 1

The reaction
`(\(CaO\))` (s) +
`(\(CO_2\))` (g) →
`(\(CaCO_3\))` (s) is not an oxidation-reduction reaction, as there are no changes in the oxidation states of the elements involved.

The chemical equation
`\(CaO (s) + CO_2 (g) → CaCO_3 (s)\)` represents the formation of calcium carbonate from calcium oxide and carbon dioxide. Despite involving changes in the arrangement of atoms, this reaction is not classified as an oxidation-reduction (redox) reaction because there is no alteration in the oxidation states of the elements.

Oxidation-reduction reactions involve the transfer of electrons between elements, resulting in changes in their oxidation states. In this specific reaction, calcium oxide
`(\(CaO\))` reacts with carbon dioxide
`(\(CO_2\))` to form calcium carbonate
`(\(CaCO_3\)).` The oxidation states remain constant: calcium
`(\(Ca\))` maintains an oxidation state of +2, oxygen
`(\(O\))` retains -2, and carbon
`(\(C\))` preserves +4.

The lack of change in oxidation states indicates that no electron transfer occurs, and as such, it does not meet the criteria for an oxidation-reduction reaction. Instead, this reaction is a synthesis reaction where two substances combine to form a new compound. Understanding the nature of chemical reactions and their classification helps elucidate the underlying principles governing chemical transformations.