Science Chapter 2: Acids, Bases and Salts

A comprehensive set of vocabulary flashcards based on the lecture notes for Chapter 2: Acids, Bases and Salts, including chemical definitions, reactions, and pH indicators.

Acids

Substances that are sour in taste and change blue litmus to red, such as $HCl$ and $H_2SO_4$.

Bases

Substances that are bitter in taste and change red litmus to blue, such as $NaOH$ and $KOH$.

Indicators

Substances that indicate the presence of an acid or base in a solution, like litmus solution, red cabbage, and turmeric.

Litmus solution

A natural indicator extracted from Lichens that is a purple dye.

Olfactory indicators

Substances that show odour changes in acidic or basic media, such as onion and clove.

Methyl orange

A synthetic indicator that turns red with acids and yellow with bases.

Phenolphthalein

A synthetic indicator that remains colourless in acidic solutions and turns pink in basic solutions.

Dilute Acid

An acid solution containing only a small amount of acid and a large amount of water.

Concentrated Acid

An acid solution containing a large amount of acid and a small amount of water.

Pop test

A test conducted for hydrogen gas where a burning candle burns with a 'Pop' sound when brought near the gas.

Sodium Zincate

The salt produced when sodium hydroxide ($NaOH$) reacts with zinc ($Zn$), with the formula $Na_2ZnO_2$.

Lime water Test

A test for $CO_2$ where gas is passed through lime water ($Ca(OH)_2$), turning it milky due to the formation of a white precipitate of $CaCO_3$.

Neutralisation Reaction

A reaction between a base and an acid that produces salt and water, nullifying the effects of both.

Basic oxides

Metallic oxides that react with acids to produce salt and water.

Acidic oxides

Non-metallic oxides that react with bases to produce salt and water.

Hydronium ion

The ion formed when an $H^+$ ion associates with a water molecule, represented as $H_3O^+$.

Alkali

A base that dissolves in water, such as $NaOH$, $KOH$, or $Mg(OH)_2$.

Exothermic reaction

A reaction that releases heat, such as the process of mixing acid or base with water.

pH scale

A scale measuring from $0$ (very acidic) to $14$ (very alkaline) used to find the strength of an acid or base; 'pH' comes from the German word 'Potenz' meaning power.

Neutral pH

A $pH$ value of $7$, which represents a neutral solution such as water.

Strong Acid

An acid that gives rise to more $H^+$ ions, such as $HCl$, $H_2SO_4$, and $HNO_3$.

Weak Acid

An acid that gives rise to fewer $H^+$ ions, such as $CH_3COOH$ and $H_2CO_3$.

Antacids

Basic substances used to neutralize excess stomach acid and provide relief from indigestion.

Acid Rain

Rain water with a $pH$ of less than $5.6$.

Neutral Salts

Salts formed from a strong acid and a strong base, having a $pH$ value of $7$.

Acidic Salts

Salts formed from a strong acid and a weak base, having a $pH$ value less than $7$.

Basic Salts

Salts formed from a strong base and a weak acid, having a $pH$ value more than $7$.

Chlor-alkali process

The preparation method for sodium hydroxide ($NaOH$) through the electrolysis of aqueous sodium chloride ($NaCl$), producing chlorine and a base.

Bleaching Powder

Chemically known as $CaOCl_2$, it is prepared by the action of chlorine on dry slaked lime ($Ca(OH)_2$).

Baking Soda

Chemically known as sodium hydrogen carbonate ($NaHCO_3$), it produces $CO_2$ on heating which makes cakes and pastries spongy.

Washing Soda

Chemically known as $Na_2CO_3 \cdot 10H_2O$, it is produced by the recrystallisation of sodium carbonate.

Water of crystallisation

The fixed number of water molecules present in one formula unit of a salt.

Gypsum

A salt containing water of crystallisation with the formula $CaSO_4 \cdot 2H_2O$.

Plaster of Paris

Chemically known as $CaSO_4 \cdot \frac{1}{2}H_2O$, it is obtained by heating gypsum at $373\,K$.