Acids, Bases and Salts - Class 10 Chemistry Revision

Vocabulary practice flashcards covering key chemical formulas, reactions, definitions, and concepts from Class 10 CBSE Chapter 2: Acids, Bases and Salts.

Strong Acid

An acid that dissociates completely in water to yield a high concentration of $H^+$ ions, such as Hydrochloric acid ($HCl$), Sulphuric acid ($H_2SO_4$), and Nitric acid ($HNO_3$).

Plaster of Paris

A compound with the chemical formula $CaSO_4 \frac{1}{2}H_2O$ (Calcium sulphate hemihydrate) prepared by heating gypsum ($CaSO_4 \frac{2}H_2O$) at $373\,K$ ($100\,^\circ C$); it hardens upon mixing with water and is used for making moulds, casts, fireproofing materials, and chalks.

Chlor-Alkali Process

An industrial process used to manufacture sodium hydroxide ($NaOH$) by the electrolysis of brine ($NaCl$ solution), producing chlorine gas ($Cl_2$) and hydrogen gas ($H_2$) as byproducts: $2NaCl(aq) + 2H_2O(l) \rightarrow 2NaOH(aq) + Cl_2(g) + H_2(g)$.

Bleaching Powder

Calcium oxychloride ($CaOCl_2$), produced by reacting chlorine gas ($Cl_2$) with dry slaked lime ($Ca(OH)_2$): $Ca(OH)_2(aq) + Cl_2(g) \rightarrow CaOCl_2(s) + H_2O(l)$.

Washing Soda

A basic salt with the chemical formula $Na_2CO_3 10H_2O$ prepared by the recrystallisation of sodium carbonate ($Na_2CO_3(s) + 10H_2O(l) \rightarrow Na_2CO_3 10H_2O(s)$), which is used to remove permanent hardness of water.

Acid Dilution Safety Rule

The safety procedure of adding concentrated acid slowly to water with constant stirring, rather than adding water to acid, because dilution is a highly exothermic process that can cause heat buildup and severe splashing.

Neutralisation Reaction

A chemical reaction between an acid and a base to form a salt and water, represented as: $NaOH(aq) + HCl(aq) \rightarrow NaCl(aq) + H_2O(l)$.

Acidic Salt

A salt formed when a strong acid reacts with a weak base (e.g., $HCl + NH_4OH \rightarrow NH_4Cl + H_2O$), resulting in an aqueous solution with a pH below $7$.

Basic Salt

A salt formed when a weak acid reacts with a strong base (e.g., $NaOH + H_2CO_3 \rightarrow NaHCO_3 + H_2O$), resulting in an aqueous solution with a pH above $7$.

Neutral Salt

A salt formed when a strong acid reacts with a strong base (e.g., $NaOH + HCl \rightarrow NaCl + H_2O$), resulting in a solution with a pH equal to $7$.

Lime Water Test for Carbon Dioxide

A qualitative test where $CO_2$ gas is bubbled through lime water ($Ca(OH)_2$), turning it milky due to insoluble calcium carbonate ($CaCO_3$) formation: $Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$.

Water of Crystallisation

The fixed number of water molecules present in one formula unit of a crystalline salt, such as $2$ in Gypsum ($CaSO_4 2H_2O$), $10$ in Washing Soda ($Na_2CO_3 10H_2O$), and $5$ in Hydrated Copper Sulphate ($CuSO_4 5H_2O$).

Olfactory Indicators

Substances whose odor changes depending on whether they are mixed in acidic or basic media, such as vanilla extract, clove oil, and onion.

Litmus

A natural acid-base indicator extracted from lichen that turns red in acidic solutions, blue in basic solutions, and remains purple in neutral solutions.

Rock Salt

The natural crystalline form of sodium chloride ($NaCl$), often brownish in appearance due to impurities, which formed by the evaporation of ancient oceans millions of years ago.

Reaction of Copper (II) Oxide with Hydrochloric Acid

A reaction where black copper (II) oxide ($CuO$) dissolves in dilute $HCl$ to yield a bluish-green solution of cupric chloride ($CuCl_2$) and water: $CuO(s) + 2HCl(aq) \rightarrow CuCl_2(aq) + H_2O(l)$.

Thermal Decomposition of Lead Nitrate

A reaction in which lead nitrate is heated to form lead oxide, oxygen gas, and brown fumes of nitrogen dioxide ($NO_2$): $2Pb(NO_3)_2(s) \rightarrow 2PbO(s) + 4NO_2(g) + O_2(g)$.

Thermal Decomposition of Copper (II) Nitrate

A reaction where blue copper (II) nitrate powder is heated to produce black copper oxide ($CuO$), oxygen gas ($O_2$), and brown nitrogen dioxide gas ($NO_2$): $2Cu(NO_3)_2(s) \rightarrow 2CuO(s) + 4NO_2(g) + O_2(g)$.

Hydrangea Flower pH Effect

A natural bio-indicator phenomenon where Hydrangea plants develop blue flowers in acidic soil due to higher availability of aluminium, and pink flowers in alkaline soil.

Role of Toothpaste in Tooth Decay

Toothpastes are basic substances that prevent tooth decay by neutralising the excess acids produced by bacteria breaking down food particles in the mouth.