SALTS, ACIDS AND BASES, Study notes of Chemistry

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Acids, Bases &

Salts: Vocabulary

Ms. Roberts

1. Acids

❖ Corrosive when in concentrate form ❖ Sour to taste ❖ Have a pH of 1-6; very strong acids have a pH of 1 ❖ Change blue litmus paper red; cause litmus paper to turn red ❖ Aqueous solutions of acids conduct electricity

Characteristics of Acids

Chemical Characteristics of Acids

Acids react with M.A.Z.I.T metals (Mg, Al, Zn, Fe & Sn: the reactive metals) to form a salt and hydrogen gas

Acids react with carbonates and bicarbonates to form a salt, CO 2 and water

Acids react with bases to form a salt and water

Types of Acids

Cont’d

Acid anhydrides are compounds that

react with water to form acids.

These compounds are mainly acidic

oxides of non-metals.

Examples of acid anhydrides:

● Sulfur trioxide (SO 3 )

● Nitrogen dioxide (NO 2 )

● Carbon dioxide (CO 2 )

Types of Acids Cont’d

Acid anhydride literally means “an acid without water”

2. Bases

Base vs Alkali

A base is a substance that contains hydroxide ions

(OH-) and oxide ions (O2-). They’re also defined as

proton acceptors

An alkali is a soluble base, i.e. a base which dissolves

in water to produce hydroxide ions (OH-). All alkalis

are bases but not all bases are alkalis

Chemical Characteristics of Alkalis

★ Strong alkalis completely ionise in water ★ Weak alkalis are only partially ionised in aqueous solution

● Ammonia is a common alkaline gas that is soluble in water and produces ammonium and hydroxide ions when dissolved. Ammonia is used as a base

Chemical Characteristics of Alkalis

● Bases react with ammonium salts (ammonium salts are substances with a NH 4 +^ ion. They are acidic in nature) to form ammonia gas, a salt and water

https://youtu.be/lxSsf4w9hOg?si=bXu_gegVJ9XpYFAq

Chemical Characteristics of Alkalis Cont’d

Amphoteric oxides and hydroxides are Z.A.P metal oxides & hydroxides that react with both acids and bases

Zn [Zinc oxide (ZnO)] Al [Aluminium oxide (Al 2 O 3 )] Pb [Lead(II) oxide (PbO)]

Zn(OH)2, Zinc hydroxide Al(OH)3, Aluminium hydroxide Pb(OH)2, Lead hydroxide

Compare Acidic,

Basic, Neutral and

Amphoteric Oxides

What Really is a

Salt?

A salt is a compound formed when metal ions or the ammonium ion takes place of some or all the replaceable hydrogen ion(s) of an acid

A normal salt is formed when all H+^ ions are replaced. Only monobasic acids form normal salts

An acid salt is formed from dibasic and tribasic acids where some H+^ ions have been replaced but the salt retains H+^ ions from the original acid