Salts

How is a salt formed

A salt is a substance formed when a metal ion or ammonium ion replaces all or some of replaceable H+ ions in an acid

What are the two parts of a salt

Metal: cation (comes from the base)

Non-metal or radical: anion (comes from the acid)

What are the different types of salts

• Acid salts

• Normal salts

What are acid salts

Acid salts still contain some replaceable H+ ions from the acid. These have a pH below 7

What are normal salts

Normal salts contain no replaceable H+ ions. These have a pH of 7 or neutral

What happens when dibasic and tribasic acids are partially neutralized

Dibasic and tribasic acids form acid salts if they are partially neutralized

Explain water of crystallization

• This is when some salts contain water within their crystal structure which are called HYDRATED SALTS

• This water can be driven off by gentle heating to give ANHYDROUS OR DRY SALTS

• The salt can be rehydrated by adding water

Solubility of Salts

When heating salts what can they undergo

Thermal decomposition and thermal dissociation

What is Thermal Decomposition

• When some salts are heated then break down and decompose. Some salts decompose faster than others due to the position of the metal in the reactivity series

• Metals higher up in the reactivity series form salts form salts that are THERMAL STABLE, while those lower down form salts that decompose more easily when heated

General Thermal Decomposition

What is Thermal Dissociation

Thermal dissociation is when a compound decomposes on heating but the products rejoin on cooling

What is Double Decomposition

• Double decomposition occurs when two salt solutions are added together and exchange ions

• If an insoluble salt forms during double decomposition, a precipitate forms. These reaction is called PRECIPITATION REACTION