The Essential Roles of Salts in Science and Daily Life

Salts are ionic compounds composed of positively charged ions (cations) and negatively charged ions (anions). Salts play vital roles in various biological and chemical processes, from maintaining electrolyte balance in the human body to participating in chemical reactions in industry and agriculture. Their diverse properties make them integral to numerous aspects of science and daily life.

Salt Families: Exploring the Common Bonds of Sodium and Chloride in Chemicals

• Salts having the same positive or negative radicals are said to belong to a family. 
  • Example: NaCl and Na₂SO₄ belong to the family of sodium salts. 
  • Similarly, NaCl and KCl belong to the family of chloride salts.

pH of Acid,Bases and salts

• Neutral: Salts of a strong acid and a strong base are neutral with a pH value of 7.
• Acidic: Salts of a strong acid and weak base are acidic with pH value less than 7 and
• Basic: Salts of a strong base and weak acid are basic in nature, with pH value more than 7.

Common Salt :Transformation from Sodium Chloride to Everyday Chemical elements

• Combination: The salt formed by the combination of hydrochloric acid and sodium hydroxide solution is called sodium chloride. 
• Rock Salt: Deposits of solid salt are also found in several parts of the world and are often brown due to impurities. This is called rock salt. 
  • Beds of rock salt were formed when seas of bygone ages dried up. 
  • Rock salt is mined like coal.
• Common salt – A raw material for chemicals: The common salt is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda, bleaching powder and many more.

Different Substances: The Realm of Acid, Bases and Salts

• Sodium Hydroxide: When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium hydroxide. 
  • The process is called the chlor-alkali process because of the products formed – chlor for chlorine and alkali for sodium hydroxide. 

• • Chlorine gas is given off at the anode, and hydrogen gas at the cathode. 

• • Sodium hydroxide solution is formed near the cathode.

2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g)

• Bleaching Powder: Chlorine is produced during the electrolysis of aqueous sodium chloride (brine) and is used for the manufacture of bleaching powder. 
  • Bleaching powder (CaOCl₂) is produced by the action of chlorine on dry slaked lime [Ca(OH)₂].

                    Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

• • Uses of Bleaching Powder –

1. 1. 1. For bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry;
      2. As an oxidising agent in many chemical industries; and
      3. To make drinking water free from germs.

• Baking Soda: The baking soda is commonly used in the kitchen for making tasty crispy pakoras, etc. Sometimes it is added for faster cooking. 
  • The chemical name of the compound is sodium hydrogen carbonate (NaHCO₃).  
  • It is produced using sodium chloride as one of the raw materials.

NaCl + H₂O + CO₂ + NH₃ → NH₄Cl (Ammonium chloride)+NaHCO₃(Sodium Hydrogencarbonate)

• • When it is heated during cooking the following reaction takes place;

2NaHCO₃  → Na2CO₃ (Sodium carbonate) + H₂O + CO₂ 

• Uses of Baking Soda:

1. For making baking powder, which is a mixture of baking soda (sodium hydrogencarbonate) and a mild edible acid such as tartaric acid.
   1. When baking powder is heated or mixed in water  the following reaction takes place,

      NaHCO₃ + H+ (From any acid)  →  CO₂ + H₂O + Sodium salt of acid

      Carbon dioxide produced during the reaction can cause bread or cake to rise making them soft and spongy.

2. It is also an ingredient in antacids. Being alkaline, it neutralises excess acid in the stomach and provides relief.
3. It is also used in soda-acid fire extinguishers.

• Washing Soda: Another chemical that can be obtained from sodium chloride is Sodium carbonate – Na₂CO₃.10H₂O (washing soda). 
  • Recrystallisation of sodium carbonate gives washing soda. It is also a basic salt. The journey from sodium chloride to washing soda exemplifies the transformative influence of acid,bases and salts in our daily lives.

Na₂CO₃ + 10 H₂O → Na₂CO₃.10H₂O

• Uses of washing soda –

1. 1. Sodium carbonate is used in glass, soap and paper industries.
   2. It is used in the manufacture of sodium compounds such as borax.
   3. Sodium carbonate can be used as a cleaning agent for domestic purposes.

Hydrated Salt Dynamics: An Exploration of Water of Crystallisation in Copper Sulphate, Gypsum, and the Journey to Plaster of Paris

• Copper sulphate crystals which seem to be dry contain water of crystallisation. 
  • When the crystals are heated, this water is removed and the salt turns white. 
  • If we moisten the crystals again with water, then the blue colour of the crystals reappears.
• Water of crystallisation is the fixed number of water molecules present in one formula unit of a salt. 
• Five water molecules are present in one formula unit of copper sulphate. 

Chemical formula for hydrated copper sulphate is CuSO4.5H₂O.

• Gypsum has two water molecules as water of crystallisation. 
  • It has the chemical formula CaSO4.2H₂O.
• On heating gypsum at 373 K, it loses water molecules and becomes calcium sulphate hemihydrate (CaSO4.1/2H₂O). 
  • This is called Plaster of Paris, the substance which doctors use as plaster for supporting fractured bones in the right position.

• • Plaster of Paris is a white powder and on mixing with water, it changes to gypsum once again giving a hard solid mass.

CaSO4. 1/2 H₂O + 11/2 H₂O → CaSO4.2H₂O

• • Plaster of Paris is used for making toys, materials for decoration and for making surfaces smooth.

Conclusion

• Chemical changes involving acid, bases and salts prove to be paramount in shaping our daily lives, giving rise to new substances with unique properties
  • The chemical changes can be represented by the chemical equation.
  • Also the chemical properties of these substances play an important part in our daily life in many ways.

DOWNLOAD PDF