Which of the following compounds can be used to obtain free nitrogen?

The correct answer is option 1. \(NaNO_2\).

When sodium nitrite \(NaNO_2)\) is heated, it undergoes thermal decomposition to produce nitrogen gas \((N_2)\) along with other products. Here is a detailed explanation of the reaction:

Decomposition of Sodium Nitrite:

When solid sodium nitrite \((NaNO_2)\) is heated strongly, it decomposes into sodium nitrite \((NaNO)\), oxygen gas \((O_2)\), and nitrogen gas \((N_2)\).

The overall balanced chemical equation for the decomposition reaction can be represented as:

\(2NaNO_2 \rightarrow 2NaNO + O_2 \)------- (1)

\(2NaNO \rightarrow Na_2O + N_2 \) --------(2)

Explanation of the Reaction:

In the first step of the reaction (equation 1), solid sodium nitrite decomposes into sodium nitrite \((NaNO)\) and oxygen gas \((O_2)\). This step is characterized by the liberation of oxygen gas. In the second step of the reaction (equation 2), sodium nitrite \((NaNO)\) further decomposes into sodium oxide \((Na_2O)\) and nitrogen gas \((N_2)\). This step is characterized by the release of nitrogen gas.

Obtaining Free Nitrogen:

The formation of nitrogen gas \((N_2)\) in the second step of the reaction results in the release of free nitrogen. Nitrogen gas \((N_2)\) is obtained as a product of the decomposition of sodium nitrite, making sodium nitrite a suitable compound for obtaining free nitrogen.

Practical Applications:

This decomposition reaction of sodium nitrite can be utilized to produce nitrogen gas in laboratory settings or industrial processes where a source of free nitrogen is required. The production of nitrogen gas from sodium nitrite can be employed in various applications, such as in chemical synthesis, inert atmosphere creation, and as a source of nitrogen for chemical reactions.

In summary, when heated, sodium nitrite decomposes to produce nitrogen gas, making it a suitable compound for obtaining free nitrogen. This decomposition reaction is a practical method for obtaining nitrogen gas in various laboratory and industrial applications.