Acid-base reactions are important in both industrial chemistry and biochemistry. Every day people encounter acid-base reaction products at pharmacies, homes, shops, and even at work. A popular example of these products is sodium chloride which is found in common salt. This paper explains in detail the chemical reaction involved when acids and bases react. It focuses on the chemical process that takes place when hydrochloric acid and ammonia are mixed. Acids are chemical substances that produce H+ ions when dissolved in water.
pH Scale
The pH scale is used to determine the basicity or acidity of a solution. pH scale gives a convenient method of determining the amount of hydrogen ion (H+) concentration in acidic or basic solution. Adding pure water to acid causes an increase in the concentration of hydrogen ions and decreases hydroxide ions. Adding pure water to a base increases the concentration of hydroxide ions and decreases that of H+ ions. The pH scale, which is an inverse logarithm, ranges from zero to fourteen (Mohammed et al., 2007). Acidic solutions range from 0 to 6.9, while alkaline/basic solutions range from 7.1-14. Substances that have a pH scale of 7.0 are neutral. Hydrochloric acid has a pH scale of 3.01, while ammonia has a pH scale of about 11. The concentration of H+ ions is very high in hydrochloric acid solution and very low in ammonia solution.
Strong and Weak Bases and Acids
Strong acids react completely with water to yield hydrogen ions and anions, while strong bases, on the other hand, dissociate fully in water to produce hydroxide ions and cation. Only a small percentage of molecules of weak bases and acids react with pure water to yield ions. Strong bases and acids are strong electrolytes, while weak bases are said to be weak electrolytes. Hydrochloric acid is a strong acid, while ammonia is a weak base.
Acid-Base Reaction
A neutralization reaction is the process that takes place after acid and base react (Mohammed et al., 2007). Salt is the product of an acid-base reaction, which is a combination of the acid anion and the base cation. When ammonia (base) is reacted with hydrochloric acid, it produces ammonium chloride (salt). Ammonium chloride consists of Cl– anions and NH4+ cations.
HCL (aq) + NH3 (aq) → NH4Cl (aq)
However, this reaction doesn’t result in the product of water; only salt is produced. Ammonium chloride was first invented by Ernest Solvay who was a Belgian chemist in 1861. It was formed as by-product in a chemical reaction as he attempted to produce sodium carbonate.
Energy Changes
When ammonia and hydrogen chloride gases are reacted, the exothermic reaction below occurs. Exothermic reaction refers to the processes resulting in realizing of energy to the surroundings. The energy usually comes in form of light or heat.
Ammonia + hydrogen chloride ↔ ammonium chloride + heat.
The reaction between hydrogen chloride and ammonia produces ammonium chloride and heat. The reaction is reversible since ammonium chloride is thermally decomposable to ammonia gas and hydrogen chloride gas.
Buffer System
A buffer solution withstands changes in pH when an acid or basic component is added. It involves an acid-base combination with the base and acid varying by absence or proton presence, respectively (Mohammed et al., 2007). Ammonium chloride is a buffer solution. When hydrochloric acid is added to the buffer system, the additional H+ ions are absorbed by NH3 to form NH4. Since all the additional H+ ions have consumed and formed NH4, which is a weaker base, the buffer system’s pH can withstand changes significantly.
Uses of Ammonium Chloride
Ammonium chloride is majorly used in manufacturing nitrogenous fertilizers, mostly used for crops like wheat and rice. Besides, ammonium chloride is used as a constituent in manufacturing contact explosives, fireworks, and safety matches (Mohammed et al., 2007). It is also used as a flux in processing metals to be soldered, tin-coated, and galvanized. Henceforth is used in yeast nutrient in the process of making bread. However, ammonium chloride is moderately harmful since it causes difficulty in breathing, nausea, skin irritation, headache, and cough. This is mostly due to inhaling ammonium chloride fume form.
Reference
Mohammed, O. F., Pines, D., Nibbering, E. T., & Pines, E. (2007). Base‐induced solvent switches in acid–base reactions. Angewandte Chemie, 119(9), 1480-1483. Web.