Chemical Reactions, Acids, Bases, and Salts Vocabulary

Vocabulary flashcards covering core definitions, reactions, chemical indicators, salts, and chemical processes from Chapters 1 and 2.

Litmus Solution

A purple dye extracted from lichen, a plant belonging to the division Thallophyta, which is commonly used as an acid-base indicator.

Olfactory Indicator

A substance whose odour changes in acidic or basic media, such as finely chopped onions, vanilla essence, or clove oil.

Neutralisation Reaction

The reaction between an acid and a base to yield a salt and water, generally represented as $\text{Base} + \text{Acid} \rightarrow \text{Salt} + \text{Water}$.

Basic Oxide

A metallic oxide that reacts with acids to produce a salt and water, behaving similarly to a base.

Hydronium Ion

A positively charged ion formed when a hydrogen ion combines with a water molecule, represented as $H_3O^+$ or $H^+(aq)$.

Alkali

A base that dissolves in water, characterized by being soapy to touch, bitter in taste, and corrosive.

Dilution

The process of mixing an acid or a base with water, resulting in a decrease in the concentration of ions ($H_3O^+$ or $OH^-$) per unit volume.

pH Scale

A scale for measuring hydrogen ion concentration in a solution, running from 0 (very acidic) to 14 (very alkaline), with 7 representing neutral.

Acid Rain

Rainwater that has a pH value less than 5.6 due to dissolved atmospheric pollutants.

Calcium Hydroxyapatite

A crystalline form of calcium phosphate that makes up tooth enamel, serving as the hardest substance in the human body.

Water of Crystallisation

The fixed number of water molecules present in one formula unit of a salt, such as five water molecules in hydrated copper sulphate ($CuSO_4 \times 5H_2O$).

Plaster of Paris

Calcium sulphate hemihydrate ($CaSO_4 \times \frac{1}{2}H_2O$), a white powder obtained by heating gypsum at $373\,K$.

Chlor-Alkali Process

The process of passing electricity through an aqueous solution of sodium chloride (brine), decomposing it into sodium hydroxide ($NaOH$), chlorine gas ($Cl_2$) at the anode, and hydrogen gas ($H_2$) at the cathode.

Bleaching Powder

A chemical compound represented as $Ca(ClO)_2$, produced by the action of chlorine gas on dry slaked lime ($Ca(OH)_2$).

Baking Soda

Sodium hydrogencarbonate ($NaHCO_3$), a mild non-corrosive basic salt used in cooking, antacids, and soda-acid fire extinguishers.

Washing Soda

Recrystallised sodium carbonate ($Na_2CO_3 \times 10H_2O$), a basic salt used in glass, soap, and paper industries, as well as for removing permanent hardness of water.

Skeletal Chemical Equation

An unbalanced chemical equation in which the total mass and number of atoms of each element are not equal on both sides.

Combination Reaction

A chemical reaction in which a single product is formed from two or more reactants, such as $CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq)$.

Exothermic Chemical Reaction

A reaction in which heat energy is released along with the formation of products.

Endothermic Reaction

A chemical reaction in which energy is absorbed from the surroundings in the form of heat, light, or electricity.

Decomposition Reaction

A chemical reaction in which a single reactant breaks down to yield two or more simpler products.

Thermal Decomposition

A decomposition reaction carried out by heating a substance.

Displacement Reaction

A chemical reaction in which a more reactive element displaces or removes another element from its compound solution.

Double Displacement Reaction

A chemical reaction in which there is an exchange of ions between the reactants to form new compounds.

Precipitate

An insoluble solid substance produced during a chemical reaction in an aqueous solution.

Oxidation

A chemical process in which a substance gains oxygen or loses hydrogen during a reaction.

Reduction

A chemical process in which a substance loses oxygen or gains hydrogen during a reaction.

Redox Reaction

An oxidation-reduction reaction in which one reactant is oxidised while another is reduced simultaneously.

Corrosion

The process in which a metal is attacked and damaged by atmospheric substances around it, such as moisture, air, and acids.

Rancidity

The state produced by the oxidation of fats and oils in food materials left for a long time, leading to an unpleasant change in smell and taste.