Acids, Bases and Salts Lecture Notes

Flashcards covering the definitions, classification, strength, properties, and preparation methods of acids, bases, and salts as per the provided lecture notes and syllabus scope.

Acid (General Definition)

A compound which when dissolved in water yields hydronium ions $(H_3O^+)$ as the only positively charged ions.

Base

A compound (oxide or hydroxide of a metal) which reacts with hydronium ions of an acid to give salt and water only.

Alkali

A base that is soluble in water and yields hydroxyl ions $(OH^-)$ as the only negatively charged ions in aqueous solution.

Organic Acid

An acid derived from plant sources, such as citric acid, oxalic acid, tartaric acid, and acetic acid.

Inorganic (Mineral) Acid

An acid derived from minerals, such as $HCl$, $H_2SO_4$, and $HNO_3$.

Hydracid

An acid containing hydrogen and a non-metallic element other than oxygen, such as $HCl$, $HBr$, and $HI$.

Oxyacid

An acid containing hydrogen, another element, and oxygen, such as $HNO_3$ and $H_2SO_4$.

Strong Acid

An acid which dissociates almost completely in aqueous solution, producing a high concentration of hydrogen ions ($H^+$ or $H_3O^+$).

Weak Acid

An acid which dissociates only partially in aqueous solution, resulting in a low concentration of hydrogen ions and containing both molecules and ions.

Basicity of Acid

The number of hydrogen ions $(H^+)$ which can be produced per molecule of the acid in aqueous solution, or the number of hydroxyl ions with which one molecule of an acid combines.

Monobasic Acid

An acid that ionizes in aqueous solution to produce one hydrogen ion per molecule, such as $HCl$, $HNO_3$, and $CH_3COOH$.

Acetic Acid Basicity

Contains four hydrogen atoms but is monobasic because it ionizes in aqueous solution to produce only 1 hydrogen ion per molecule.

Acidity of Base

The number of hydroxyl ions $(OH^-)$ that can be produced per molecule of the base in aqueous solution, or the number of hydrogen ions with which a molecule of a base combines.

Monoacidic Base

A base that ionizes in aqueous solution to produce one hydroxyl ion per molecule, such as $NaOH$, $KOH$, and $NH_4OH$.

Arrhenius Theory

States that acids are substances which dissociate in aqueous solution to give $H^+$ ions.

Lowry-Bronsted Theory

Defines acids as proton donors and bases as proton acceptors, where a proton is $(H^+)$.

Hydronium Ion ($H_3O^+$) Formation

Formed when a proton $(H^+)$ released from an acid adds to the lone pair of electrons on the oxygen atom of a water molecule via a coordinate covalent bond.

Coordinate Covalent Bond

A bond formed between an atom of a polar covalent molecule with a lone pair of electrons and an ion which accepts that lone pair.

Neutralization

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

Heat of Neutralization

The amount of heat liberated when 1 gram equivalent of an acid or a base is completely neutralized.

Acid Rain

Precipitation (rain, snow, or fog) with a pH less than $5.6$, caused by pollutants like sulphur dioxide $(SO_2)$ and nitrogen oxides.

Indicators

Weak organic compounds (acids or bases) which change colour in accordance with the pH of the solution.

pH Value

The negative logarithm (to the base 10) of the hydrogen ion concentration expressed in moles per litre: $pH = -log_{10}[H^+]$.

Universal Indicator

A mixture of organic dyes or mixed indicators (like pH paper) that indicates the strength or pH range of a solution by giving different colours at different pH values.

Salt

A compound formed by the partial or complete replacement of the replaceable hydrogen ion of an acid by a metallic ion or ammonium ion.

Acid Salt

A salt formed by the partial replacement of the replaceable hydrogen ions of an acid molecule by a basic radical, such as $NaHSO_4$.

Normal Salt

A salt formed by the complete replacement of the replaceable hydrogen ions of an acid molecule by a basic radical, such as $Na_2SO_4$.

Basic Salt

A salt formed by the partial replacement of the hydroxyl radicals of a diacidic or triacidic base with an acid radical, such as $Cu(OH)NO_3$.

Double Salt

Formed by mixing saturated solutions of two simple salts followed by crystallization, such as Potash Alum $K_2SO_4 \text{ } Al_2(SO_4)_3 \text{ } 24 H_2O$.

Mixed Salt

A salt containing two or more basic radicals or acid radicals, such as bleaching powder $Ca(OCl)Cl$.

Complex Salt

A salt that dissociates to yield a simple ion and a complex ion, such as sodium silver cyanide $Na[Ag(CN)_2]$.

Nessler's Reagent

Potassium mercuric iodide $K_2[HgI_4]$, used for testing Ammonia gas.

Titration

A laboratory procedure used to determine the completion of a neutralization reaction, typically used for preparing soluble salts from an alkali and a dilute acid.

Passivity (Lead Salts)

The formation of an insoluble coating (like $PbSO_4$) on a reactant (like $PbCO_3$ or $Pb(OH)_2$) that prevents further reaction with acids like dilute sulphuric acid.

Water of Crystallisation

The amount of water molecules which enter into loose chemical combination with one molecule of a salt during crystallization from its aqueous solution.

Deliquescence

A property where water-soluble salts absorb moisture from the atmosphere, dissolve in it, and change into a solution (e.g., $FeCl_3$, $MgCl_2$).

Efflorescence

A property where crystalline hydrated salts lose their water of crystallisation partly or completely upon exposure to the atmosphere, changing into a powder.

Hydrolysis of Salts

A reaction in which salts react with water to form a base (alkali) and an acid, resulting in an acidic, alkaline, or neutral solution.