Sodium bicarbonate, also known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3 and the IUPAC designation sodium hydrogencarbonate. A sodium cation (Na+) and a bicarbonate anion (HCO3) combine to form this salt. Sodium bicarbonate is a white, crystalline substance that is commonly found as a fine powder. It tastes slightly salty and alkaline, like washing soda (sodium carbonate).
Chemical name – Sodium hydrogen carbonate
Chemical formula – NaHCO3
Preparation (Solvay process):
a. Limestone is heated: CaCO3→CaO+CO2
b. CO2 is passed through a concentrated solution of sodium chloride and ammonia:
NaCl(aq)+NH3(g)+CO2(g)+H2O(l)→NaHCO3(aq)+NH4Cl(aq)
Uses:
- Reduces the acidity in the stomach
- Acts as an antacid which is used to treat stomach upset and indigestion
- Used in the process of washing as a water softener
Washing soda
Chemical name – Sodium hydrogen carbonate
Chemical formula – NaHCO3
Preparation (Solvay process) –
a. Limestone is heated: CaCO3 → CaO + CO2
b. CO2 is passed through a concentrated solution of sodium chloride and ammonia:
NaCl(aq) + NH3(g) + CO2(g) + H2O(l) → NaHCO3(aq) + NH4Cl(aq)
Uses
1. In glass, soap and paper industries
2. Softening of water
3. Domestic cleaner
Crystals of salts
Certain salts form crystals by combining with a definite proportion of water. The water that combines with the salt is called water of crystallisation.
The process by which a solid forms, in which the atoms or molecules are strongly arranged into a structure known as a crystal, is known as crystallisation. Precipitation from a solution, freezing, and, more rarely, direct deposition from a gas are some of the ways crystals form.
Example:
Table salt (sodium chloride or halite crystals), sugar (sucrose), and snowflakes are examples of common materials that form crystals. Many gemstones, such as quartz and diamond, are crystals.