Problem 158 - A Complete Resource Book in Chemistry for JEE Main

Question

Calomel \(\left(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\right)\) on reaction with ammonium hydroxide gives (a) \(\mathrm{HgO}\) (b) \(\mathrm{Hg}_{2} \mathrm{O}\) (c) \(\mathrm{HgNH}_{2} \mathrm{Cl}\) (d) \(\mathrm{NH}_{2}-\mathrm{Hg}-\mathrm{Hg}-\mathrm{Cl}\)

Step-by-Step Solution

Answer

(c) \(\mathrm{HgNH}_{2}\mathrm{Cl}\).

Step 1: Identify the Chemical Reaction

When calomel (\(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\)) is treated with ammonium hydroxide (\(\mathrm{NH}_{4}\mathrm{OH}\)), it undergoes a reaction to form a different compound. Our task is to determine the product(s) formed from this reaction.

Step 2: Recall the Reaction Products

Inorganic mercury compounds like calomel, when reacted with ammonia or ammonium compounds, typically form amido-mercury compounds. Specifically, calomel reacts with ammonium hydroxide to form a compound containing the amido-mercury group (\(\mathrm{HgNH}_{2}\)).

Step 3: Determine the Correct Amido Compound

The likely outcome of the reaction between calomel and ammonium hydroxide is the formation of \(\mathrm{HgNH}_{2}\mathrm{Cl}\), which contains one amino group and one chlorine atom bonded to a mercury atom.

Step 4: Confirm the Reaction Product

Given the multiple-choice answers, the compound \(\mathrm{HgNH}_{2}\mathrm{Cl}\) specifically matches option (c). Therefore, the primary product of this reaction is \(\mathrm{HgNH}_{2}\mathrm{Cl}\).

Key Concepts

Inorganic Mercury Compounds

Inorganic mercury compounds are chemical substances that contain mercury bonded to other elements besides carbon. These compounds have a wide range of uses and are often found in various chemical processes and applications. One common inorganic mercury compound is calomel, also known as mercurous chloride, which has the chemical formula \( \mathrm{Hg}_{2} \mathrm{Cl}_{2} \). This compound is known for its use in medicine and in various industrial processes.

Some attributes of inorganic mercury compounds include:

• Presence of mercury (Hg) in either the +1 or +2 oxidation state.
• Generally having low solubility in water.
• Potential toxicity, requiring careful handling and usage to prevent mercury exposure.

Additionally, when these compounds react with other chemicals, like ammonium hydroxide, they can create unique products, such as amido-mercury compounds. Understanding the reactions and products of such compounds is important in chemistry for both practical applications and safety measures.

Ammonium Hydroxide

Ammonium hydroxide, a solution of ammonia in water, is commonly denoted as \( \mathrm{NH}_{4}\mathrm{OH} \). It is a versatile reagent used in various chemical reactions and industrial processes. This chemical is particularly useful due to its alkaline properties, making it an excellent source of hydroxide ions and valuable in many reactions.

Key characteristics of ammonium hydroxide include:

• It's a weak base that partially dissolves in water to form hydroxide ions (\( \mathrm{OH}^{-} \)).
• Often used in cleaning products, fertilizers, and as a pH regulator in chemical syntheses.
• Capable of reacting with a wide range of other compounds, including metal salts and oxides, which allows it to form various complex products.

In the reaction with calomel (\( \mathrm{Hg}_{2} \mathrm{Cl}_{2} \)), ammonium hydroxide interacts directly with mercury to form specific amido-mercury compounds, exemplifying its reactive capability in generating new chemical entities.

Chemical Reaction Products

Examining the reaction products formed in chemical processes is crucial to understanding how different chemicals interact. In the case of the reaction between calomel (\( \mathrm{Hg}_{2} \mathrm{Cl}_{2} \)) and ammonium hydroxide (\( \mathrm{NH}_{4}\mathrm{OH} \)), specific products are generated that highlight typical outcomes for reactions involving ammonia and mercurous compounds.

When these two chemicals react, an amido-mercury compound, \( \mathrm{HgNH}_{2}\mathrm{Cl} \), is formed. This product results from the interaction of ammonia with mercury, leading to the incorporation of an amino group into the resultant compound. Key points about these products include:

• They usually contain an amido group (\( \mathrm{NH}_{2} \)), which bonds to mercury atoms and replaces other ligands.
• Such transformations often lead to a change in chemical properties, including solubility and reactivity patterns compared to the original mercury compounds.
• Understanding the composition of these products is essential for predicting outcomes in chemical synthesis and recognizing the nature of reaction intermediates.

Through such reactions, chemists can explore the diverse chemistry of inorganic compounds and their potential applications in various fields.