How Is Ammonium Bicarbonate Produced and Used in Chemistry?
Ammonium bicarbonate is an inorganic compound that is mildly basic. It consists of the ammonium cation and the bicarbonate anion. The molecular or chemical formula of Ammonium bicarbonate is NH4HCO3. It appears as a crystalline solid white and has a strong smell of ammonia. It readily dissolves in water but insoluble in most various organic solvents. When Ammonium bicarbonate is dissolved in water, it gives you a mildly alkaline solution.
Ammonium Bicarbonate Structure
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Properties of Ammonium Bicarbonate
Salt of Hartshorn
The compositions contain ((NH4)2CO3) which is the chemical name of ammonium carbonate. They were produced commercially and formerly referred to as spirits of ammonia or salt of hartshorn. It is obtained by the dry distillation of nitrogenous organic matter like hair, horn, leather. In addition to ammonium bicarbonate, this material contains carbamate (NH4CO2NH2), and carbonate ((NH4)2CO3). Ammonium Carbonate may be a non-toxic white crystalline salt with the formula (NH4)2CO3. It is also known as hartshorn or baker’s ammonia.
Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as a smelling salt. It was a predecessor to the more modern leavening agents baking soda and baking powder. It is also used in some smokeless tobacco products and as an active ingredient in cough syrup to relieve the symptoms of bronchitis. Its use as a leavening agent goes back centuries. It is the predecessor to the more modern leavening agents baking soda and baking powder. A similar decomposition takes place when the carbonate is exposed to air.
Ammonium Bicarbonate Production
Ammonium bicarbonate is produced by combining CO2 and ammonia:
CO2 + NH3 + H2O → (NH4) HCO3
The reaction solution is kept cold because ammonium bicarbonate is thermally unstable. It allows the precipitation of the merchandise as white solid. About 100,000 tons were produced during this way in 1997.
The compound on exposure to air gives off ammonia and returns to ammonium bicarbonate form. Ammonia gas converts (NH4)2CO3, and H2O) into normal carbonate ((NH4)2CO3) when it passes into a robust solution of the carbonate (a 2:1:1 mixture of (NH4)HCO3. It may obtain in the crystalline condition from an answer prepared at about 30 °C.
Ammonium Bicarbonate Uses
Ammonium bicarbonate is employed within the food industry as a leavening agent for flat food, like cookies and crackers. It was commonly utilized in the house before modern-day leaven was made available. In many cases, it replaces bicarbonate of soda or a mixture of both, counting on the recipe composition and leavening requirements. Compared to baking soda, hartshorn has the advantage of producing more gas for the same amount of agent, and of not leaving any salty or soapy taste in the finished product, because it completely decomposes into water and gaseous products that evaporate during baking. It cannot be used for moist, bulky food, like regular bread or cakes since some ammonia is going to be trapped inside and can cause an unpleasant taste.
Ammonium bicarbonate is used as an inexpensive nitrogen fertilizer in China but is now being phased out in favour of urea for quality and stability. This compound is employed as a component of fire-extinguishing compounds, pharmaceuticals, dyes, pigments, and it is also an essential fertilizer, being a source of ammonia within the production. It widely remains utilized in the plastics and rubber industry, in the manufacture of ceramics, in chrome leather tanning, and for the synthesis of catalysts.
It is also used for buffering solutions to form them slightly alkaline during chemical purification, like high-performance liquid chromatography. Because it entirely decomposes to volatile compounds, this enables rapid recovery of the mixture of interest by freeze-drying. Ammonium bicarbonate is additionally a vital component of the expectorant cough syrup.
Health Effects/Safety Hazards of Ammonium Bicarbonate
In low concentrations, it is not considered hazardous. Its primary health hazard is its decomposition reaction giving sour ammonia gas, which is a severe irritant. Inhalation of ammonium bicarbonate can irritate the eyes, skin, nose, and full system respiratory, and cause severe coughing and difficulty in breathing.
FAQs on Ammonium Bicarbonate: Structure, Properties & Applications
1. What is ammonium bicarbonate, and what is its chemical formula?
Ammonium bicarbonate is an inorganic compound, specifically the bicarbonate salt of the ammonium ion. It is a white, crystalline solid with the chemical formula NH₄HCO₃. It is formed from the reaction of a weak base (ammonium hydroxide) and a weak acid (carbonic acid), which contributes to its relative instability.
2. Can you explain the chemical structure of ammonium bicarbonate?
The structure of ammonium bicarbonate is ionic. It is composed of two primary ions: the ammonium cation (NH₄⁺) and the bicarbonate anion (HCO₃⁻). The ammonium ion has a tetrahedral geometry with the nitrogen atom at the center. The bicarbonate ion has a trigonal planar arrangement of oxygen atoms around the central carbon atom.
3. What are the key physical and chemical properties of ammonium bicarbonate?
Ammonium bicarbonate has several distinct properties that are important for its applications:
- Appearance: It is a white, crystalline solid at room temperature.
- Odour: It has a faint odour of ammonia due to its slow decomposition.
- Solubility: It is soluble in water but insoluble in most organic solvents like alcohol and acetone.
- Thermal Stability: It is thermally unstable and begins to decompose at temperatures as low as 36 °C, releasing ammonia, carbon dioxide, and water.
- pH: A solution of ammonium bicarbonate in water is slightly alkaline, typically with a pH around 7.8.
4. What are the primary uses and applications of ammonium bicarbonate?
The main application of ammonium bicarbonate is as a leavening agent in the baking industry, where it is often called baker's ammonia or hartshorn. It helps dough rise by releasing carbon dioxide and ammonia gas. Other important applications include:
- Manufacturing of porous plastics, ceramics, and dyes.
- As a component in some fire extinguishers.
- As a source of nitrogen in some fertilizers.
- In analytical chemistry as a reagent.
5. How is ammonium bicarbonate different from baking soda (sodium bicarbonate) and baking powder?
These are all leavening agents but differ chemically:
- Ammonium Bicarbonate (NH₄HCO₃): Decomposes with heat to form ammonia gas, carbon dioxide gas, and water. It leaves no solid residue, making it ideal for creating a light, crisp texture.
- Baking Soda (NaHCO₃): Is a single chemical, sodium bicarbonate. It requires an acidic ingredient in the recipe to react and produce carbon dioxide gas. Without an acid, it can leave a soapy-tasting residue (sodium carbonate).
- Baking Powder: Is a complete leavening agent. It is a mixture that contains baking soda, a dry acid (like cream of tartar), and a stabilizer (like cornstarch). It reacts with moisture and heat, not requiring an external acid from the recipe.
6. Why is ammonium bicarbonate used for thin, dry baked goods like cookies but not for moist cakes?
This is due to one of its decomposition products: ammonia (NH₃), which has a strong, pungent odour. When used in thin and dry baked goods like crackers or cookies, the high surface area and low moisture allow the ammonia gas to completely bake off and escape during cooking. However, in thick and moist items like cakes or muffins, the ammonia gas gets trapped within the batter, imparting an unpleasant chemical taste and smell to the final product.
7. What happens when ammonium bicarbonate is heated? Explain its thermal decomposition.
When heated, ammonium bicarbonate undergoes an endothermic thermal decomposition reaction. It breaks down into three gaseous products: ammonia (NH₃), carbon dioxide (CO₂), and water (H₂O). This is why it is an effective leavening agent, as all products are gases that contribute to the rising of dough. The balanced chemical equation is:
NH₄HCO₃(s) + heat → NH₃(g) + CO₂(g) + H₂O(g)
8. Why is ammonium bicarbonate considered a thermally unstable compound?
Ammonium bicarbonate's instability stems from its chemical nature as a salt of a weak acid (carbonic acid, H₂CO₃) and a weak base (ammonium hydroxide, NH₄OH). Salts formed from weak acids and weak bases are prone to hydrolysis and have relatively weak ionic attractions. A small amount of energy, such as gentle heat, is sufficient to overcome these forces and cause the compound to decompose back into its more stable constituent molecules (ammonia, water, and carbon dioxide).
9. Is it safe to use ammonium bicarbonate in food, and what are the key safety precautions?
Yes, ammonium bicarbonate is generally recognized as safe (GRAS) by food safety authorities for use in baking. The key safety consideration is that it must be used in appropriate quantities and only in food products where its decomposition products, particularly ammonia gas, can fully dissipate during the cooking process. Ingesting the unreacted powder can cause irritation. It is crucial not to confuse it with household or industrial ammonia solutions, which are toxic and not for consumption.
