Question

The fast reaction between water and sodium is an example of:

• A. Reduction
• B. Oxidation
• C. Intramolecular redox
• D. Intermolecular redox

Answer 1

The correct option is D

Intermolecular redox

Explanation for correct option:

D. Intermolecular redox

Redox reaction:

• The reaction in which oxidation and reduction take place simultaneously is known as the Redox reaction.

Reaction between water and sodium:

• When sodium metal reacts with water, it produces sodium hydroxide and hydrogen gas is evolved.
• The chemical reaction can be depicted as:

$$\begin{gathered} 2\mathrm{Na}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{NaOH}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \left(\mathrm{Sodium}\right)\left(\mathrm{Water}\right)(\mathrm{Sodium}\mathrm{hydroxide})(\mathrm{Hydrogen}) \end{gathered}$$

Intermolecular redox reactions are those in which redox reactions occur when two different molecules react. In this reaction, two molecules are reacting together. Initially, the oxidation state of sodium was $0$. After the reaction, its oxidation state increases to $+1$. So, sodium undergoes oxidation while Hydrogen is reduced to $0$ oxidation state.

Explanation for incorrect options:

A. Reduction is the loss of oxygen.

B. Oxidation is the gain of oxygen.

C. Intramolecular redox reactions are those in which redox reactions occur within a single molecule.

Hence, option D is the correct option i.e. Intermolecular redox.