Acids, Bases & Salts – Vocabulary Flashcards

Vocabulary flashcards summarising key terms and definitions from the lecture on common salt, its derivatives, related industrial processes, and associated chemical concepts.

Rock Salt

Naturally occurring, brownish deposits of solid sodium chloride (NaCl) formed by evaporation of ancient oceans; also called halite or crystalline common salt.

Common Salt

Sodium chloride (NaCl) used as a raw material to manufacture NaOH, bleaching powder, baking soda and washing soda.

Chlor-alkali Process

Electrolysis of brine that yields chlorine gas at the anode, hydrogen gas at the cathode and sodium hydroxide (alkali); named for the simultaneous production of chlorine and an alkali.

Brine

An aqueous solution of sodium chloride (NaCl, common salt) employed as the electrolyte in the chlor-alkali process.

Caustic Soda

Common name for sodium hydroxide (NaOH), a strong alkali obtained from the chlor-alkali process; used in degreasing metals, making soaps, detergents, paper and artificial fibres.

Bleaching Powder

Calcium oxychloride, Ca(OCl)₂, produced when chlorine reacts with dry slaked lime; used for bleaching cotton, wood pulp, disinfecting water and as an oxidising agent.

Washing Soda

Sodium carbonate decahydrate, Na₂CO₃·10H₂O, a basic salt used in glass, soap, paper industries, domestic cleaning and removal of permanent water hardness.

Water of Crystallization

Fixed number of water molecules chemically bound within one formula unit of a crystalline salt, e.g., CuSO₄·5H₂O or Na₂CO₃·10H₂O.

Baking Soda

Sodium hydrogen carbonate, NaHCO₃, a mild basic salt used in cooking, antacids and soda-acid fire extinguishers.

Baking Powder

A mixture of baking soda and tartaric acid; on heating releases CO₂ that makes cakes and bread rise, neutralising soda’s bitter taste.

Gypsum

Calcium sulphate dihydrate, CaSO₄·2H₂O, which yields plaster of Paris when heated to about 373 K.

Plaster of Paris (POP)

Calcium sulphate hemihydrate, CaSO₄·½H₂O, a white powder that hardens on mixing with water; used for casts, décor and wall finishing.

Anhydrous Copper Sulphate

White CuSO₄ obtained by heating hydrated copper sulphate; turns blue crystals white by losing water of crystallization.

Hydrated Copper Sulphate

Blue crystals of CuSO₄·5H₂O that lose colour and water on heating, illustrating water of crystallization.

Alkali

A water-soluble base that produces OH⁻ ions in solution; examples include NaOH obtained in the chlor-alkali process.

pH Drop in Milk

Curd formation occurs when lactic acid lowers milk’s pH below 6; making milk slightly alkaline delays souring by neutralising the acid.

Carbonic Acid in Rainwater

CO₂ from air dissolves in rain to form H₂CO₃, supplying H⁺ ions that make rainwater weakly acidic and electrically conductive.

Fizzing with Acids & Magnesium

Hydrogen gas evolution when an acid reacts with magnesium metal; stronger acids (e.g., HCl) produce more vigorous fizzing than weak acids (e.g., CH₃COOH).