What Is The Function of Ammonium Chloride in Dry Cells?

What is the function of ammonium chloride in dry cell? Ammonium chloride is a salt compound that contains ammonium and chlorine, It is used as a deicer on roads, as an agent in the textile manufacturing process, electrolyte in dry cell batteries, as well as a fertilizer. In dry cell batteries, the ammonium chloride serves two purposes: it lowers the operating voltage of the battery and regulates hydrogen ion concentration in electrodes.

The function of Ammonium Chloride in Dry Cell

Lower Battery Voltage

Ammonium chloride is added to the dry cell battery instead of water, decreasing the operating voltage to 0.9V. This can be explained by hydrogen ion concentration being closely related to voltage, and ammonium chloride regulates this concentration.

PH Regulation

Ammonium chloride is decomposed in dry cell batteries forms ammonia gas and hydrogen ions. Because of the changes in pH caused by decomposition, some side reactions occur, resulting in the battery's self-discharge. Ammonia gas is very soluble in water to dissolve into electrodes. The hydrogen ions are transported to the zinc electrode by ammonium ion (NH4+) and form hydrogen gas.

Important Tips

Since ammonia gas is corrosive, it causes negative effects on all of the components of batteries. As hydrogen ions get transported to the zinc plate, they cause an increase in pH and a decrease in solubility of zinc hydroxide, which causes a depletion of zinc ions from the electrode surface. The pH increase also decreases the solubility of manganese dioxide and negative carbonates plate.

Ammonium chloride's function in dry cell batteries can be summarized as four points:

1) It increases hydrogen ion concentration, which allows the voltage of the battery to drop;

2) It regulates pH in electrodes;

3) It decomposes into ammonia gas and hydrogen ions;

4) Helps in self-discharging of the battery.

Advantages of Ammonium Chloride in Dry Cells

Ammonium chloride is an inexpensive, environmentally friendly, and commonly used electrolyte. It has good chemical and thermal stability. It doesn't cause side reactions since ammonium chloride's decomposition products are non-toxic and easily washed away, making dry cells safe to use and reducing the need for special disposal.

Ammonium chloride is preferred to other electrolytes, such as ammonium nitrate and zinc chloride, because it has a more consistent performance. For example, in high temperatures where oxidizing agents are used more rapidly, the performance of ammonium nitrate declines. Ammonium chloride doesn't cause any chemical changes at elevated temperatures.

What are the Properties of Ammonium Chloride?

Ammonium chloride is an ionic compound composed of ammonium and chloride ions. It's obtained from aqueous ammonia and hydrogen chloride gas under high pressure or through liquid-phase hydrolysis. Ammonium chloride forms colorless to white crystalline powder or granules when it comes in contact with air, and it's odorless but has a strong saline taste. When mixed with water, it forms a strongly alkaline solution and releases heat. It only burns at high temperatures (~600 ℃) but also absorbs moisture from the air to form anhydrous ammonia chloride, which is highly flammable.

Ammonium chloride's chemical formula is NH4Cl, and its molar mass is 53.49 g/mol. Its density is 0.918 g/cm³, and it's in the form of a white crystalline powder or granules when it comes in contact with air.

Ammonium chloride's melting point is 250℃, and boiling point is 613 ℃. Its heat of vaporization is 35 kJ/mol. The heat of fusion is 1.8 kJ/mol, so it's a powerful dehydrating agent under normal conditions. When ammonium chloride comes in contact with water, it forms an alkaline solution that can have a pH of up to 12.

What are the Hazards of Ammonium Chloride?

Ammonium chloride is non-flammable, but it's corrosive. It can irritate skin and cause burns in mucous membranes or eyes. If ammonium chloride has come in contact with the skin, the area should be washed thoroughly with soap and water. It can cause respiratory tract irritation, while ingestion can lead to nausea, vomiting, and diarrhea. It's also harmful when it comes in contact with the eyes.

Ammonium chloride reacts violently with oxidizing agents or nitrates, so proper care should be taken while handling the chemical because of its toxicity. Since ammonium chloride is hygroscopic, it absorbs moisture from the air, so it should be stored in an air-tight container. Ammonium chloride is incompatible with acetylene, nitrogen dioxide, or nitric acid.

Conclusion

Function of ammonium chloride in dry cell batteries is to regulate the pH of electrodes by decomposing into ammonia gas and hydrogen ions. It also increases the concentration of hydrogen ions, which allows the voltage of batteries to drop. Finally, ammonium chloride causes the self-discharging of batteries due to its ionization process.