Question

Describe a laboratory and an industrial preparation of nitrogen gas.

Short answer

Nitrogen in the lab: Heat ammonium nitrite. Industrially: Fractional distillation of liquid air.

Step-by-step solution

Laboratory Preparation Method - Introduction

In the lab, nitrogen gas can be prepared by heating ammonium nitrite. The reaction is generally carried out under controlled conditions to avoid any side reactions.

Laboratory Preparation Method - Chemical Reaction

The reaction for the laboratory preparation of nitrogen gas is:\[NH_4NO_2 (s) ightarrow N_2 (g) + 2H_2O (l)\]Here, ammonium nitrite decomposes to give nitrogen gas and water as byproducts.

Industrial Preparation Method - Introduction

Industrial production of nitrogen is typically done through the fractional distillation of liquid air. This process takes advantage of the different boiling points of the gases present in air.

Industrial Preparation Method - Fractional Distillation Process

In fractional distillation, air is first liquefied by cooling it to extremely low temperatures and then allowing it to warm up slowly. Nitrogen, which has a lower boiling point (-195.8°C) than oxygen, boils off first and is collected.

Industrial Preparation Method - Separation and Collection

As the air mixture is warmed, nitrogen gas is separated from other gases, particularly oxygen, due to its lower boiling point. This ensures that the nitrogen collected is pure.

Key concepts

Laboratory Methods

In laboratory settings, nitrogen gas is usually prepared by using ammonium nitrite. This method is both simple and effective for small-scale production. Ammonium nitrite, a stable compound under normal conditions, decomposes upon heating. During this process, it breaks down into nitrogen gas and water. To do this safely, the reaction is conducted in controlled environments to prevent any unwanted reactions. Here is the balanced chemical equation for this reaction: \[ NH_4NO_2 (s) \rightarrow N_2 (g) + 2H_2O (l) \]This straightforward setup makes it ideal for educational purposes and small research labs, providing an easy way to study nitrogen without the complications of larger-scale methods.

Industrial Methods

For industrial purposes, nitrogen is most commonly produced through a technique called fractional distillation of liquid air. Air, mainly composed of nitrogen and oxygen, is liquefied by reducing the temperature to extremely low levels. This process needs extensive and advanced cooling systems due to the very low temperatures involved. In its liquid state, air consists of distinct gases that can be separated due to differences in their boiling points. Fractional distillation is highly efficient for producing large quantities of nitrogen, which is valuable not only for industrial applications but also for serving as a base material in many chemical processes.

Chemical Reactions

Chemical reactions that produce nitrogen gas are crucial for both laboratory and industrial preparation methods. In the laboratory, the decomposition of ammonium nitrite is a prominent example of a straightforward reaction that liberates nitrogen. Besides ammonium nitrite decomposition, other chemical reactions involve compounds like azides or ammonia when treated under certain conditions.

• Azides like sodium azide can explosively decompose to produce nitrogen gas, often used in airbags.
• Catalytic decomposition of ammonia, though less practical than fractional distillation, remains an option in chemistry labs and smaller industries.

Each method varies in complexity and scale, demonstrating the versatility of chemical reactions in obtaining nitrogen.

Fractional Distillation

Fractional distillation is a sophisticated process integral to the industrial preparation of nitrogen. By taking advantage of varying boiling points of the components in liquid air, it efficiently separates nitrogen from oxygen and other trace gases. Initially, atmospheric air is compressed and cooled until it becomes liquid. The key undergoes further warming within a distillation column. Here, nitrogen, with a boiling point of -195.8°C, evaporates earlier than oxygen (-183°C) and can be collected as a pure gas. This method not only yields pure nitrogen but also allows simultaneous production of oxygen and argon, which are also useful industrially. Thanks to fractional distillation's efficiency, industries can continuously obtain nitrogen for uses ranging from fertilizers to inert atmospheres in manufacturing. Hence, it remains the backbone of industrial nitrogen production.