Lecture Notes: Acids, Bases, and Salts

A set of vocabulary flashcards covering the fundamental concepts of acids, bases, and salts including their definitions, classifications, and preparation methods based on the lecture transcript.

Indicator

A chemical which indicates the nature of a solution by means of a sharp change in colour.

Acid

A compound which contains one or more hydrogen atoms and when dissolved in water, produce hydronium ions ($H_3O^+$) as the only positively charged ions.

Hydronium ion

The hydrated hydrogen ion ($H_3O^+$) that exists independently in the solutions of acids.

Organic acids

Acids which are obtained usually from plants, contain carbon atoms along with hydrogen atoms, and are generally weak acids.

Inorganic acids

Also known as mineral acids, these are typically obtained from minerals and usually do not contain carbon, excluding carbonic acid ($H_2CO_3$).

Oxy-acids

Acids that contain oxygen along with hydrogen and some other element, such as nitric acid ($HNO_3$) and sulphuric acid ($H_2SO_4$).

Hydracids

Acids that contain hydrogen and a non-metallic element but do not contain oxygen, such as hydrochloric acid ($HCl$).

Basicity of an acid

The number of hydronium ions ($H_3O^+$) that can be produced by the ionisation of one molecule of that acid in aqueous solution.

Monobasic acids

Acids which on ionisation in water produce one hydronium ion per molecule of the acid.

Dibasic acids

Acids which on ionisation in water produce two hydronium ions ($H_3O^+$) per molecule of the acid.

Tribasic acids

Acids which on ionisation in water produce three hydronium ions per molecule of the acid.

Concentrated acid

An acid which contains a very small amount of water or no water.

Dilute acid

An acid which contains far more amount of water than its own mass.

Strength of an acid

A measure of the concentration of hydronium ions produced in its aqueous solution, or the number of $H^+$ ions released.

Degree of ionisation ($\alpha$)

The ratio of the number of acid molecules ionised to the total number of acid molecules present in aqueous solution, multiplied by 100.

Acidic anhydrides

Oxides, such as $SO_3$ or $CO_2$, that dissolve in water to give acids.

Olfactory indicators

Substances whose smell changes in acidic or basic solutions, such as onion, vanilla, and clove oil.

Base

A metallic oxide or hydroxide or ammonium hydroxide which reacts with hydronium ions of an acid to form salt and water only.

Alkali

A basic hydroxide which when dissolved in water produces hydroxyl ($OH^-$) ions as the only negatively charged ions.

Acidity of a base

The number of hydroxyl ions ($OH^-$) which can be produced per molecule of the base in aqueous solution.

Monoacidic base

A base that dissociates in its molten state or aqueous solution to produce one $OH^-$ ion per molecule of that base.

pH scale

A scale ranging from 0 to 14 devised by Sorensen to represent the hydronium ion concentration of a given aqueous solution.

Universal indicator

A mixture of several different pH indicators that gives a spectrum of colors depending on the hydronium ion concentration.

Salt

An ionic compound which dissociates in water to yield a positive ion other than hydrogen and a negative ion other than hydroxyl.

Normal salt

A salt formed by the complete replacement of the ionisable hydrogen atoms of an acid by a metallic or an ammonium ion.

Acid salt

A salt formed by the partial replacement of the ionisable hydrogen atoms of a polybasic acid by a metal or ammonium ion.

Basic salt

A salt formed by the partial replacement of the hydroxyl group of a di- or tri-acidic base by an acid radical.

Neutralisation

The process by which $H^+$ ions of an acid react completely with the $OH^-$ ions of a base to give salt and water only.

Heat of neutralisation

The amount of heat liberated when one gram equivalent of an acid or a base is completely neutralised.

Titration

The process of conducting a neutralisation reaction between a soluble base and an acid to determine the exact volume required for complete reaction.