Problem 3 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Reaction of ammonia with excess \(\mathrm{Cl}_{2}\) gives: [Main Sep. 05, 2020 (II)] (a) \(\mathrm{NH}_{4} \mathrm{Cl}\) and \(\mathrm{N}_{2}\) (b) \(\mathrm{NH}_{4} \mathrm{Cl}\) and \(\mathrm{HCl}\) (c) \(\mathrm{NCl}_{3}\) and \(\mathrm{NH}_{4} \mathrm{Cl}\) (d) \(\mathrm{NCl}_{3}\) and \(\mathrm{HCl}\)

Step-by-Step Solution

Answer

The reaction produces \\(\mathrm{NCl}_3\\) and \\(\mathrm{HCl}\\), i.e., option (d).

Step 1: Identify Reaction Components

In this problem, we have ammonia \(\mathrm{NH}_3\) reacting with chlorine \(\mathrm{Cl}_2\). We are told that chlorine is in excess.

Step 2: Predict Reaction Outcomes

Ammonia \(\mathrm{NH}_3\) can react with excess \(\mathrm{Cl}_2\) in two main steps: 1. \(6 \mathrm{NH}_3 + 3 \mathrm{Cl}_2 \rightarrow 6 \mathrm{NH}_4\mathrm{Cl} + \mathrm{N}_2\) (if all ammonia reacts to completion, forming ammonium chloride and nitrogen gas). 2. Ammonia reacts further in the presence of excess chlorine to form nitrogen trichloride \(\mathrm{NCl}_3\) and hydrochloric acid \(\mathrm{HCl}\). Thus, \(\mathrm{4 NH}_3 + 3 \mathrm{Cl}_2 \rightarrow \mathrm{NCl}_3 + 3 \mathrm{HCl}\).

Step 3: Match Predicted Products to Options

Based on the predictions, the reaction of \(\mathrm{NH}_3\) with excess \(\mathrm{Cl}_2\) would primarily produce nitrogen trichloride \(\mathrm{NCl}_3\) and hydrochloric acid \(\mathrm{HCl}\). This matches option (d).

Key Concepts

Chemical Reactions

Chemical reactions are processes where substances change into different substances. In the context of ammonia and chlorine reaction, the molecules rearrange to form new products. The reaction involves

• Ammonia ( \( \mathrm{NH}_3 \)) reacting with chlorine ( \( \mathrm{Cl}_2 \)).
• Chlorine is used in excess, meaning there is more chlorine compared to ammonia.

This ensures full reaction and the formation of additional products when the reaction components remain after initial reactions.

In a chemical reaction, reactants are the starting materials. As they interact, they may break and form molecular bonds, creating different substances known as products. The balance of the reaction is important, represented by coefficients, to maintain the conservation of mass.

Understanding chemical reactions is crucial to predict the products that will be formed. For this particular reaction, two possibilities arise, one providing ammonium chloride and nitrogen gas, and the other yielding nitrogen trichloride and hydrochloric acid.

Ammonium Chloride

Ammonium chloride ( \( \mathrm{NH}_4\mathrm{Cl} \)) is one product of the reaction between ammonia and chlorine. It is a white, crystalline salt.

Formed when ammonia reacts with chlorine in a balanced manner (using just enough chlorine, not excess), it can generate:

• Ammonium chloride as the primary product
• Nitrogen gas as a secondary product

The equation that demonstrates this is:

\[ 6 \mathrm{NH}_3 + 3 \mathrm{Cl}_2 \rightarrow 6 \mathrm{NH}_4\mathrm{Cl} + \mathrm{N}_2 \]

This reaction is often conducted in a controlled environment to ensure correct quantities lead to desired products without excess ammonia or chlorine, except when aiming to produce different outcomes like nitrogen trichloride. Ammonium chloride is used in many applications, including fertilizers and in the medical field.

Nitrogen Trichloride

Nitrogen trichloride ( \( \mathrm{NCl}_3 \)) is a compound that forms from the reaction of ammonia with an excess amount of chlorine. It results when ammonia's quantity is insufficient to consume all the chlorine present, leading to the formation of distinct products.

The reaction can be expressed as:

\[ 4 \mathrm{NH}_3 + 3 \mathrm{Cl}_2 \rightarrow \mathrm{NCl}_3 + 3 \mathrm{HCl} \]

Here are some interesting facts about nitrogen trichloride:

• It is a yellow, oily liquid at room temperature.
• It is explosive and must be handled very carefully.
• Its presence indicates that chlorine was in excess during the reaction.

This compound's explosiveness is why careful calculations and considerations are made when conducting such reactions in industrial processes. Knowing about nitrogen trichloride helps to understand the potential risks and necessary precautions when dealing with reactive chemicals, particularly chlorine and ammonia.