Question

In Kjeldahl's method of estimation of nitrogen, \(\mathrm{K}_{2} \mathrm{SO}_{4}\) acts as: (a) Catalytic agent (b) Boiling point elevator (c) Hydrolysis agent (d) Oxidizing agent

Short answer

The answer is (b) Boiling point elevator.

Step-by-step solution

Understanding the Kjeldahl Method

Kjeldahl's method is a laboratory technique used to determine the nitrogen content in organic compounds. The process involves the digestion of the organic material to convert nitrogen into ammonium sulfate.

Role of K2SO4 in Kjeldahl's Method

In the Kjeldahl method, potassium sulfate (B}_2SO_4) is added to increase the boiling point of the digestion mixture. This ensures that the reaction mixture remains at a higher temperature, promoting the efficient conversion of nitrogen into ammonium sulfate.

Identifying the Function of K2SO4

Potassium sulfate does not act as a catalyst, oxidizing, or hydrolyzing agent. By raising the boiling point, it allows the reaction to occur efficiently without evaporating the components at lower temperatures.

Determine the Correct Answer

Given that potassium sulfate (B}_2SO_4) is primarily used to elevate the boiling point, the correct answer to the question is option (b) Boiling point elevator.

Key concepts

Nitrogen Estimation

Nitrogen estimation is a significant process in organic chemistry, particularly in agricultural and biological sciences. The method commonly utilized for this purpose is known as Kjeldahl’s method. This technique determines the nitrogen content in organic substances, which is crucial for understanding the nutritional value of agricultural products or analyzing the protein content in food samples.

The procedure starts by digesting the organic compound with concentrated sulfuric acid ( H_2SO_4). During digestion, nitrogen atoms in the organic compound are converted into ammonium ions ( NH_4^+ ). These ions then react with sulfate ions ( SO_4^{2-} ) to form ammonium sulfate ( (NH_4)_2SO_4 ).

• This transformation is vital as it changes nitrogen into a form that can be easily quantified.
• The amount of ammonium sulfate formed directly correlates to the original nitrogen content.

After digestion, the solution is made alkaline by adding a strong base like sodium hydroxide ( NaOH ), which releases ammonia ( NH_3 ) gas. This ammonia is distilled into a known volume of standard acid solution, and its concentration is measured through titration.

Thus, the Kjeldahl method provides a reliable and accurate way to estimate the amount of nitrogen in organic compounds, ultimately providing insights into the chemical composition of the sample.

Boiling Point Elevation

In the context of Kjeldahl’s method, boiling point elevation plays a crucial role. This phenomenon refers to the increase in the boiling temperature of a liquid when a solute is added. In Kjeldahl’s method, potassium sulfate ( K_2SO_4 ) is added to the digestion mixture.

By adding K_2SO_4 , the boiling point of the sulfuric acid solution is elevated.

• This higher boiling point means the solution can reach and maintain higher temperatures during digestion without evaporating the liquid.
• Higher temperatures enhance the efficiency of converting organic nitrogen into ammonium ions.

Moreover, maintaining a high temperature is essential for breaking down complex organic structures, which may otherwise require longer digestion times or result in incomplete conversion.

Effectively, the role of K_2SO_4 as a boiling point elevator is critical to ensuring the completeness and efficiency of the nitrogen conversion reaction in Kjeldahl’s method.

Organic Chemistry Techniques

Organic chemistry involves numerous methods and techniques for analyzing and modifying organic compounds. Kjeldahl's method is one of the many analytical techniques used in organic chemistry to quantify nitrogen, which is an indicator of protein content in the sample.

The Kjeldahl method itself combines several fundamental chemistry techniques:

• Digestion: This involves using a concentrated acid to break down organic material into simpler substances.
• Titration: A common laboratory procedure used to determine the concentration of an analyte in solution by reacting it with a reagent of known concentration.
• Distillation: This process separates components based on differences in their boiling points, useful for isolating ammonia gas in Kjeldahl’s method.

Each of these techniques demonstrates important principles in organic chemistry. Understanding these methods is vital for chemistry students and professionals as they are widely applied in research, quality control, and product development. Moreover, mastering such techniques can help solve complex problems and advance innovations in chemical industries.