When calcium oxide (CaO) reacts with sodium metal (Na), a redox (reduction-oxidation) reaction occurs. In this process, sodium metal gets oxidized, and calcium oxide gets reduced, leading to the formation of sodium oxide and calcium metal.
This chemical interaction highlights the relative reactivity of the two metals, where the stronger reducing power of sodium allows it to displace calcium from its oxide.
The reaction between calcium oxide and sodium metal is a classic example of a redox reaction, where electrons are transferred between reactants. Based on the provided reference, the specific roles of each reactant are clearly defined:
Roles of Reactants
- Sodium Metal (Na): Acts as the reducing agent. It readily gains oxygen (or loses electrons) during the reaction.
- Calcium Oxide (CaO): Acts as the oxidizing agent. It loses oxygen (or gains electrons) during the reaction.
What Gets Oxidized and Reduced?
As per the reference:
- Oxidized: Na (Sodium Metal) – Sodium loses electrons and gains oxygen, forming sodium oxide.
- Reduced: CaO (Calcium Oxide) – Calcium oxide gains electrons and loses oxygen, forming calcium metal.
The Chemical Transformation
The overall reaction can be represented by the following chemical equation:
CaO (s) + 2Na (s) → Na₂O (s) + Ca (s)
Here's a breakdown of the changes:
- Calcium (Ca): In calcium oxide (CaO), calcium is in the +2 oxidation state. After the reaction, it is reduced to elemental calcium (Ca), which is in the 0 oxidation state. This signifies a gain of electrons and the loss of oxygen.
- Sodium (Na): Elemental sodium (Na) is in the 0 oxidation state. During the reaction, it is oxidized to form sodium oxide (Na₂O), where sodium is in the +1 oxidation state. This signifies a loss of electrons and a gain of oxygen.
Why Does This Reaction Occur?
Sodium is a highly reactive alkali metal and is a stronger reducing agent than calcium. This means sodium has a greater tendency to lose electrons and gain oxygen compared to calcium. At high temperatures, sodium can effectively reduce calcium oxide to calcium metal.
Summary of Changes
To summarize the roles and outcomes of this reaction:
| Reactant | Role | Change During Reaction | Product Formed |
|---|---|---|---|
| Sodium (Na) | Reducing Agent | Oxidized: Gains oxygen, loses electrons (0 to +1 oxidation state) | Sodium Oxide (Na₂O) |
| Calcium Oxide (CaO) | Oxidizing Agent | Reduced: Loses oxygen, gains electrons (+2 to 0 oxidation state) | Calcium Metal (Ca) |
This reaction demonstrates a fundamental concept in chemistry: the relative reactivity of metals and the principles of oxidation and reduction.
