Problem 40 - A Complete Resource Book in Chemistry for JEE Main

Question

In Kjeldahl's method of estimation of nitrogen, copper sulphate acts as (a) catalytic agent (b) silver spiral (c) hydrolyzing agent (d) oxidizing agent

Step-by-Step Solution

Answer

The answer is (a) catalytic agent.

Step 1: Understand the Kjeldahl Method

The Kjeldahl method is a procedure used in chemistry to estimate the amount of nitrogen in organic compounds. It involves digestion of the sample, where proteins are broken down by acid into ammonium sulfate.

Step 2: Identify the Role of Copper Sulphate

In the digestion phase of the Kjeldahl method, copper sulphate is added as a catalyst. It speeds up the digestion of the sample by breaking down the proteins to release nitrogen in the form of ammonium ions.

Step 3: Analyze Each Option

- (a) Catalytic agent: Copper sulphate is used to speed up reactions, which characterizes a catalytic role. - (b) Silver spiral: Not related to the function of copper sulphate. - (c) Hydrolyzing agent: This is not applicable, as copper sulphate doesn't hydrolyze compounds. - (d) Oxidizing agent: Though copper can sometimes engage in redox reactions, its role here is catalytic.

Step 4: Select the Correct Answer

Given the role of copper sulphate in the Kjeldahl method, the correct answer is that it acts as a catalytic agent.

Key Concepts

Nitrogen Estimation

Estimating nitrogen in organic compounds is a crucial part of various chemical analyses. One of the most common methods used in laboratories is the Kjeldahl method. This method helps scientists determine the nitrogen content of substances like proteins and fertilizers.
The process begins with the digestion of the organic sample. During digestion, nitrogen-containing compounds are transformed into ammonium salts using acids. The nitrogen present in the sample reacts with sulfuric acid to form ammonium sulfate. After this step, scientists distill the mixture to liberate ammonia gas, which they measure to calculate the amount of nitrogen in the sample.

• This technique provides a way to assess protein and amino acid content in food, crucial for nutritional studies.
• It is a time-tested method but requires careful handling of chemicals and precise measurement techniques.

Overall, the Kjeldahl method is vital for understanding the nitrogen levels in organic substances, essential for scientific research and industry applications.

Copper Sulphate Catalyst

In the Kjeldahl method, copper sulphate plays a fundamental role as a catalyst. Catalysts are substances that increase the rate of a chemical reaction without being consumed or permanently changed by the process. Copper sulphate is added to the digestion mixture to effectively break down proteins and accelerate the reaction.
This accelerates the conversion of organic nitrogen to ammonium sulfate, an essential step in this method. The presence of a catalyst like copper sulphate reduces the amount of time required for complete digestion, ultimately making the process more efficient and reliable.

• Copper sulphate enhances the efficacy of the sulfuric acid, ensuring more consistent results when estimating nitrogen content.
• It does not engage in the reaction as an oxidizer; instead, it serves only to quicken the reaction's pace.

Ultimately, using copper sulphate as a catalyst helps achieve more accurate nitrogen measurements in organic compounds.

Organic Compounds Chemistry

Understanding organic compounds and their composition is critical in chemistry. Organic compounds are made primarily of carbon, hydrogen, oxygen, and nitrogen. It's important to identify their elemental make-up to explore their chemical behavior and reactivity.
The Kjeldahl method is deeply rooted in this aspect of organic chemistry. By accurately estimating nitrogen, scientists can determine the protein content in food or fertilizers, for example. Comprehending the composition aids in a multitude of applications, from agricultural productivity to nutritional evaluation and pharmaceuticals.

• In organic chemistry, nitrogen is a vital element due to its prevalence in many natural and synthetic compounds.
• Accurate nitrogen estimation leads to better understanding and manipulation of organic structures.

Recognizing the content of organic compounds not only drives forward scientific knowledge but also has broad implications in various industries.