Problem 99 - A Complete Resource Book in Chemistry for JEE Main

Question

Solution of sodium metal in liquid ammonia is strongly reducing due to the presence in solution of the following (a) solvated electrons (b) sodium atoms (c) sodium hydride (d) sodium amide

Step-by-Step Solution

Answer

The solution is strongly reducing due to solvated electrons (option a).

Step 1: Understanding Sodium in Ammonia

When sodium metal is dissolved in liquid ammonia, sodium loses an electron that becomes solvated by the ammonia molecules, forming solvated electrons. These electrons are free and able to move through the solution, giving it a characteristic deep blue color.

Step 2: Identifying Reducing Agent

The solvated electrons in the solution play a key role. They are very reactive and can readily donate electrons to other compounds, thereby reducing them. This makes the solution a strong reducing agent.

Step 3: Analyzing Options

Now, analyze each option to identify which one represents the reducing species in the solution: (a) solvated electrons, (b) sodium atoms, (c) sodium hydride, and (d) sodium amide. Solvated electrons, option (a), are the species that provide the solution with its reducing properties.

Key Concepts

Solvated Electrons

When you dissolve sodium metal in liquid ammonia, something fascinating happens. The sodium atoms lose their outer electron, which then gets surrounded and stabilized by the ammonia molecules. These special electrons are known as "solvated electrons." Think of them as free agents within the solution.

Because they are surrounded by ammonia, they can move freely, giving the solution its characteristic deep blue color. They are not bound to any atom and thus are very energetic. This high energy and free state make solvated electrons quite unique. They are responsible for many interesting reactions in chemistry and are a central feature of sodium in liquid ammonia solutions. Understanding solvated electrons is crucial because they illustrate how electrons can exist independently in certain solutions, contributing significantly to the solution's properties.

Reducing Agent

A reducing agent is a substance that donates electrons to other substances during a chemical reaction. When discussing sodium in liquid ammonia, the reducing agent is the solvated electrons.

In simple words, these electrons are eager to be part of another atom or molecule, waiting to give away their extra energy. This act of donating electrons is called "reduction." With every electron they donate, solvated electrons turn the other substance from a higher oxidation state to a lower one.

• This capability makes the sodium in liquid ammonia solution a strong reducing agent, meaning it actively participates in reducing reactions.
• The presence of these free, mobile electrons, makes this solution highly reactive.

By understanding reducing agents, you can grasp how substances change and transform during reactions.

Chemical Reactions

Chemical reactions involve the rearrangement of atoms and molecules to form new substances. When it comes to sodium dissolved in liquid ammonia, the solvated electrons play a huge role in these reactions.

The deep blue solution formed is an indication of the active chemical reactivity taking place inside. When another substance enters the solution, the solvated electrons may transfer to it, initiating a chemical reaction. The type of changes that occur depends on the nature of the reacting substances.

• Sometime, it results in the formation of new compounds.
• Other times, it might lead to breaking existing chemical bonds.

In all these reactions, the solvated electrons serve as the bridge, enabling transformation through electron transfer. This process underscores the importance of electrons in facilitating and driving chemical reactions, especially in such unique solutions as sodium in liquid ammonia.