Problem 12 - A Complete Resource Book in Chemistry for JEE Main

Question

In a reaction, sodium is heated with \(\mathrm{BeCl}_{2} .\) In this reaction, sodium acts as (a) precipitating agent (b) hydrolysis agent (c) reducing agent (d) oxidizing agent

Step-by-Step Solution

Answer

Sodium acts as a reducing agent.

Step 1: Define Agents in Chemistry

In chemical reactions, different agents play distinct roles. A reducing agent donates electrons to another substance, leading to its oxidation. An oxidizing agent accepts electrons from another substance.

Step 2: Analyze the Role of Sodium

In the reaction between sodium and \( \text{BeCl}_2 \), sodium, with an electron configuration \( [\text{Ne}]3s^1 \), can easily lose one electron to form \( \text{Na}^+ \). This loss of an electron means sodium is oxidized.

Step 3: Determine the Other Species' Reaction

\( \text{BeCl}_2 \) can gain the electron lost by sodium, thus getting reduced. The gain of electrons by \( \text{BeCl}_2 \) indicates that sodium is providing the electrons necessary for this process.

Step 4: Conclusion

Since sodium loses electrons and causes \( \text{BeCl}_2 \) to be reduced, sodium acts as a reducing agent, which is the role of a substance that loses electrons in a reaction.

Key Concepts

Sodium

Sodium is a chemical element with the symbol Na. It is a member of the alkali metal group and is highly reactive, especially with water and air. This reactivity arises from its atomic structure.

It has one electron in its outermost shell, which it readily loses, making it very eager to form chemical bonds.

Some interesting characteristics of sodium include:

• It is soft and can be cut with a knife.
• Sodium reacts vigorously with water to form sodium hydroxide and hydrogen gas.
• Due to its high reactivity, sodium is not found free in nature but in compounds, like sodium chloride (table salt).

Sodium plays a vital role in various chemical reactions, especially those involving electron transfer, owing to its tendency to donate its outer electron.

Electron Loss

When a substance loses electrons, it undergoes a process known as oxidation. For sodium, this electron loss is all about transitioning from its neutral state to a positive state.

The process can be described as:\[ \text{Na} \rightarrow \text{Na}^+ + e^- \]

Here, sodium (Na) loses one electron to become a sodium ion \(\text{Na}^+\). This change in the electrical charge is fundamental in oxidation-reduction (redox) reactions.

This electron loss doesn't happen in isolation and is only part one of a bigger picture. In redox reactions, the loss of electrons by one element results in the gain of those electrons by another substance.

Oxidation-Reduction Reactions

Oxidation-reduction reactions, commonly referred to as redox reactions, are chemical reactions involving the transfer of electrons between two substances.

These reactions consist of two halves:

• **Oxidation**: The process wherein a substance loses electrons.
• **Reduction**: The process wherein a substance gains electrons.

The substance that donates electrons in a redox reaction is known as the **reducing agent**. Conversely, the substance that gains electrons is the **oxidizing agent**.

In the context of the sodium and \(\text{BeCl}_2\) reaction, sodium acts as the reducing agent because it gives an electron to \(\text{BeCl}_2\).

This donated electron helps \(\text{BeCl}_2\) reduce, while sodium itself gets oxidized. This complementary occurrence of oxidation and reduction is the cornerstone of redox chemistry.