Question

Explain the action of smelling salt, which is ammonium carbonate \(\left[\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\right]\). (Hint: The thin film of aqueous solution that lines the nasal passages is slightly basic.)

Short answer

Smelling salts release ammonia, which increases the pH in the nasal passages, stimulating inhalation reflexes.

Step-by-step solution

Understand the Composition of Smelling Salts

Smelling salts primarily contain ammonium carbonate, \[\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\].Upon exposure to air, this compound releases ammonia gas, \(\mathrm{NH}_3\), due to its volatile nature.

Reaction of Ammonia in Aqueous Solution

In the nasal passages, there is a thin film of aqueous solution that is slightly basic. When ammonium carbonate decomposes, it releases ammonia gas. Ammonia (\(\mathrm{NH}_{3}\)) can dissolve in water and form ammonium hydroxide (\(\mathrm{NH}_{4}\mathrm{OH}\)) in a basic solution:\[\mathrm{NH}_3 (g) + \mathrm{H_2O} (l) \rightleftharpoons \mathrm{NH}_4^+(aq) + \mathrm{OH}^-(aq)\]This reaction increases the pH of the solution.

Effect of Increased pH in Nasal Passages

The formation of ammonium hydroxide in the nasal passages raises the pH, making the environment more basic. This sudden change stimulates the mucous membranes in the nasal passages, which in turn triggers an inhalation reflex. This action leads to rapid breathing and an increased alertness or arousal in individuals who encounter the ammonia vapor.

Conclude the Chemical Effects

Smelling salts work by releasing ammonia, which interacts with the slightly basic environment of the nasal passages to create an alkaline reaction. The basic conditions irritate mucous membranes, triggering a reflexive response that causes the person to inhale sharply, leading to increased alertness.

Key concepts

Ammonium Carbonate

Ammonium carbonate is a chemical compound with the formula \((NH_{4})_{2}CO_{3}\). It is widely used in smelling salts because of its ability to release ammonia gas. This compound is a white crystalline solid that can decompose easily when exposed to air. This decomposition results in the release of ammonia gas, which is crucial for the working mechanism of smelling salts.

In smelling salts, ammonium carbonate serves as a source for ammonia gas, which is utilized to increase alertness. Its ease of decomposition makes it ideal for applications where quick reactions are necessary.

• Has a distinct odor due to the release of ammonia.
• Quickly decomposes upon exposure to air, facilitating its use in first aid for reviving individuals.
• Mainly used in sports and medical settings to stimulate consciousness.

Ammonia Gas

Ammonia gas, with the chemical formula \(NH_{3}\), is a colorless gas with a distinct, pungent smell. It plays a key role in the mechanism of smelling salts. When ammonium carbonate decomposes, it releases ammonia gas into the atmosphere.

Ammonia gas is particularly reactive with water, and in the context of smelling salts, it meets the aqueous solution present in our nasal passages. Here, it dissolves to form ammonium hydroxide, leading to an increase in pH. This change in the chemical environment of the nasal passages causes a reflexive response.

• Main contributor to the pungent smell that jolts one into alertness.
• Forms ammonium hydroxide upon reaction with water, making the environment more basic.
• Stimulates nasal membranes, thus enhancing alertness by triggering involuntary inhalation reflexes.

Nasal Passages

The nasal passages are covered with a thin film of aqueous solution, which plays a crucial role in the efficacy of smelling salts. This solution is naturally slightly basic. When ammonia gas is released from decomposed ammonium carbonate, it interacts with this basic solution.

The chemical interaction leads to the formation of ammonium hydroxide, further increasing the pH level and making the environment of the nasal passages even more basic. This abrupt change in pH serves as a stimulus to the mucous membranes lining the nasal passages.

• Have a natural protective function to filter and humidify air.
• Basic conditions are essential for the rapid response to ammonia gas.
• The irritation caused by the pH increase provokes a sudden and involuntary inhalation, increasing alertness and drawing more air into the lungs.