Ammonium Chloride - Structure, Formula, Preparation, Physical and Chemical Properties, Health Effects & Uses

At some point of time in our lives, we have all taken those bitter-sweet cough syrups to relieve ourselves during those tough episodes of cough and cold.

Ammonium chloride is one such saviour ingredient present in cough syrups, that functions majorly as an expectorant, which means it clears our airways off the mucus. In fact imagine, that even the samosas and jalebis that you have from your favourite restaurants use food-grade ammonium chloride (E510) for enhancing the crispiness of the outer layer of these snacks.

That must have definitely intrigued you to learn a bit more about this ‘safe to engulf’ chemical. But to what extent is it safe and how else does it act or what are its other properties, or how do we produce it? Are all produced NH₄Cl food grades? So to give answers to all such questions, let’s get into the understanding of this chemical in a little more detail.

Table of Contents

Ammonium Chloride- Description and Occurrence
Ammonium chloride- Formula and Structure
Ammonium Chloride-Preparation
Physical properties of Ammonium Chloride
Chemical properties of Ammonium Chloride
Uses of Ammonium Chloride
Pharmacological Impacts of Ammonium Chloride
Health Hazards of Ammonium Chloride
Practice Problems
Frequently Asked Questions- FAQs

Ammonium Chloride - Description and Occurrence

NH4Cl is an inorganic crystalline salt whose chemical name is Ammonium Chloride. It is also termed as sal ammoniac i.e., the salt of ammonia and hydrogen chloride. This compound has a high solubility in water and is mildly acidic. Ammonium Chloride is used in veterinary medicine for the prevention of urinary stones in animals like sheep, goats, and cattle. When ammonium sulfate and NaCl solutions react with each other, NH4Cl is formed.

When a 5% solution of ammonium chloride (by weight) is added to water, it results in a solution that has a pH value ranging from 4.6 to 6.0 and hence it is slightly acidic. Ammonium chloride is a crystalline white substance.

Ammonium chloride is found in mineralogical creations and in this form, we indicate it as the 'salt ammoniac'. Apart from this, it is also known to be present in volcanic vents and ashes. It is naturally found in burning coal dumps formed from the condensation of gases derived from coal.

Ammonium Chloride - Formula and Structure

Ammonium chloride formula is NH₄Cl and its molar mass is 53.49 g mol^-1. It is a water-soluble and mildly acidic inorganic compound. It contains an ammonium ion and a chloride ion. The structure of ammonium chloride can be represented as follows:

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The ammonium ion is tetrahedral in shape and is formed when ammonia donates its lone pair to an H⁺ ion. Ammonium ion (NH⁺₄) and chloride (Cl^-) anion are connected by an ionic bond.

Ammonium Chloride - Preparation

Ammonium chloride can be prepared by several methodologies. The first one is via the neutralization HCl with the ammoniacal residue that is made during the distillation of the coal.

NH₃(g) + HCl (aq) → NH₄Cl(s)

Ammonium chloride is also obtained as the by-product of the Solvay Process. In this process carbon dioxide and ammonia are passed into a cold saturated solution of sodium chloride.

CO₂(g) + 2NH₃(g) + 2NaCl (aq) + H₂O(l) → 2NH₄Cl (s) + Na2CO₃(s)

In the Solvay process, the sodium bicarbonate is recovered by the process of filtration, and then the ammonium chloride that remains behind in the solution gets crystallized.

Physical properties of Ammonium Chloride (NH₄Cl)

Ammonium chloride is a white crystalline solid that has no smell.
It has a density of approximately 1.5274 g mL^-1 .
The melting point and boiling point of ammonium chloride are 338 ℃ and 520 ℃, respectively.
Furthermore, it is soluble in water, ethanol, and glycerol and is slightly soluble in acetone as well.
It is insoluble in organic solvents such as ethyl acetate.
Its refractive index at 20 °C is 1.642 .
It is hygroscopic in nature.
Its standard enthapy of formation is −314.43 kJ mol^-1.

Chemical properties of Ammonium Chloride (NH₄Cl)

Ammonium chloride decomposes when strongly heated above 340 ℃ to produce HCl and NH3 gases.

Ammonium chloride reacts with sodium hydroxide to liberate ammonia and produce sodium chloride.

NH₄Cl (s)+ NaOH (aq) → NH₃(g) + NaCl (aq) + H₂O (aq)

Ammonium chloride reacts with sodium carbonate to produce sodium chloride and ammonia gas.

2NH₄Cl (s) + Na₂CO₃(s) CO₂(g) + 2NH₃(g) + 2NaCl (aq) + H₂O(l)

Ammonium chloride undergoes double decomposition reaction with KClO3 (potassium chlorate) to produce highly dangerous and reactive ammonium chlorate, which can exist as fumes when its particles are mixed into the air.

2NH₄Cl (s)+ KClO₃(aq) NH4ClO₃(s) + KCl (aq)

Uses of Ammonium Chloride

Ammonium chloride is known as an acidifying salt that can be found in the body and the urine.
Ammonium chloride guides pH regulation and has a modest diuretic impact.
This acid-forming salt is known to have an expectorant action by irritating the membranes of mucus, making it very useful for cough relief.
It is used in fertilizers as a nitrogen source, especially for crops like wheat and rice.
It is used in making various specific types of glue which help to bond plywood.
It is used in the aqueous form in Leclanche cells.
It is used as a food additive in bread making, as it acts as a yeast nutrient. Salmiak is a dark sweet in which Ammonium chloride is used to spice up. Also, it is used in food-grade form to increase the crispiness of samosa and jalebi.
Ammonium chloride is used as an acidifier.
It is utilised in cooling baths to create low temperatures.
Ammonium chloride is used as a basic buffer solution along with ammonium hydroxide (NH4OH). For example in making various shampoos, and cleaning products.
Ammonium chloride is used as a feed supplement for cattle stock.
Ammonium chloride works as a flux in metalwork during galvanization, and it helps to clean up the surface of workpieces. Ammonium chloride works as a flux in solder.

Pharmacological impacts of Ammonium Chloride

The ammonium ion (NH⁺₄) has an important role in the maintenance of acid-base balance in our body. Human kidney uses ammonium (NH⁺₄) in place of sodium (Na⁺) to combine with fixed anions in order to maintain the acid-base balance.

The medicinal usage of NH₄Cl depend upon the ability of the kidney to utilize ammonia in the excretion of an excess of fixed anions and the conversion of ammonia to urea by the liver, thereby liberating hydrogen (H⁺) and chloride (Cl^-) ions into the extracellular fluid.

Ammonium ion is converted to urea in the liver; chloride ion replaces bicarbonate.

Ammonium chloride increases acidity by increasing the amount of hydrogen ion concentrations.
Ammonium chloride can be used as an expectorant for removal of bronchial mucosa. This effect leads to the production of respiratory tract fluid which further facilitates the alleviation of effective cough.
Ammonium chloride can be used as a systemic acidifier in the treatment of severe metabolic alkalosis.
Ammonium chloride can also be used in the treatment of several urinary tract illnesses to maintain the pH level in urine.

Health Effects of Ammonium Chloride

It's not entirely risk-free, as overdosing can be a possibility. Higher blood pressure can be caused by the usage of ammonium chloride depending on a person’s medical history. Irritation, shortness of breath, cough, nausea, and headache are all different types of symptoms of ammonium chloride poisoning. Ammonium chloride in the vapour state has the potential to cause serious discomfort in the eyes. Chronic exposure can initiate an asthma-like condition or damage kidney functions.

Practice Problem

Q1. Ammonium chloride is naturally obtained from:

A. Volcanic vents
B. Sea-shells
C. Atmospheric air
D. Bauxite ore

Answer: (A)

Solution: Ammonium chloride is present in volcanic vents and ashes. It is naturally found in burning coal dumps formed from the condensation of gases derived from coal. Bauxite ore is a source of aluminium. Hence, option A is correct.

Q2. The action of ammonium chloride on sulphuric acid produces

A. ammonium sulphide
B. Ammonia gas
C. hydrogen gas
D. hydrochloric acid

Answer: (D)

Solution: When ammonium chloride reacts with sulphuric acid it produces hydrochloric acid along with ammonium sulphate.

H₂SO₄(aq) + 2NH₄Cl (aq) → 2HCl (aq) + (NH₄)₂SO₄(aq)

Q3. Ammonium chloride is an:

A. Acidic salt
B. Basic Salt
C. Complex salt
D. Neutral salt

Answer: (A)

Solution: It is an acidic salt as it is formed from the salt of strong acid (HCl) and weak base (NH4OH).

HCl (aq) + NH₄OH (aq) → NH₄Cl (aq) + H₂O (l)
NH₄Cl(aq) → NH⁺₄(aq) + Cl^-(aq)

Frequently Asked Questions- FAQs

Question1. What is the use of ammonium chloride in agriculture?
Answer: Ammonium chloride is an excellent source of nitrogen and chlorine. Also, it is useful as a nitrogen fertilization source in crops like rice and wheat. When used in a mixture with agricultural soils it increases nitrogen content in the soil and, helps enhance the soil fertility which leads to higher crop yields.

Question2. Which daily use products contain ammonium chloride?
Answer: In regular products containing ammonium chloride the major ones are- shampoo, hair colour and bleach, body wash, facial cleanser, conditioner, hand wash, dishwasher detergent as well as oil and salt. Also, it is used as an electrolyte in dry cell batteries.

Question3. What happens when ammonium chloride undergoes decomposition on heating?
Answer: When heated, ammonium chloride undergoes a decomposition reaction it evolves pungent-smelling ammonia gas and gaseous hydrogen chloride as the products.

Question4. Explain how ammonium chloride and ammonium hydroxide act as a basic buffer.
Answer: Consider a basic buffer containing a weak base NH4OH, and its salt, NH4Cl. NH₄OH(aq) ⇌ NH⁺₄(aq) + OH^-(aq)
NH₄Cl(aq) --> NH⁺₄(aq) + Cl^-(aq)

NH4Cldissociates completely and increases the concentration of NH⁺₄ which means according to Le Chatelier's principle, the equilibrium of the ionization of the weak base shifts backwards. Now dissociation of NH₄OH is suppressed and the concentration of OH^- decreases due to the presence of a common ion NH⁺₄. This is known as the common ion effect.

Case-1: If we add a small amount of OH^-to the solution, it reacts with the NH⁺₄ ions and forms NH₄OH and being a weak base and due to common ion effect, NH₄OH will not further dissociate to give OH^-. Hence, there will be less or almost no change in the pH of the solution.

Case-2: If we add a small amount of H+in the solution, then it combines with OH^-and is removed as H₂O. Hence, there will be less or almost no change in the pH of the solution.

Question5. What is the effect of mixing ammonium chloride and bleach?
Answer: Bleach is majorly composed of sodium hypochlorite which furnished chlorite ions. When bleach is mixed with ammonium chloride, a toxic gas called chloramine (NH2Cl) is produced. This gas has severe adverse effects on inhalation like coughing, nausea or even death.

NH₄Cl (aq) + NaOCl (s) --> NaCl(s) + NH₂Cl (g)+ H₂O(aq)

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