CHAPTER 8SALT

Learning Outcomes

At the end of the lessons, students should be able to:

State examples of salts used in daily lifeExplain the meaning of salt Identify soluble and insoluble saltsDescribe the preparation of soluble salts.Describe the purification of soluble salts

by recrystallisation.List physical characteristics of crystals.

Uses of salts

Food preparation• NaCl-seasoning food• MSG- enhance food taste

Food preservation• NaCl- salted fish• NaNO2 -preserve prosessed

meat

Agriculture• Nitrate salts- fertilisers

Medical• CaCO3 –antacid that

reduce acidity in the stomach of gastric patients

• Salt is formed in neutralization.• Salt : ionic compound. – anion part – acid– cation part – base

• Definition of salts

KOH(aq) + HCl(aq) KCl(aq) + H2O

A salt is a compound formed when the hydrogen ion, H+ from an acid is replaced by metal ion or ammonium ion, NH4

+.

Anion from the acid

Cation from the base

Salt Solubility

• SOLUBILITY

An ability of a compound to dissolve in solvents

Depends on the cation and anion present

Types of salts Solubility in water

Sodium , Na Ammonium Potassium ,K

All are soluble

Nitrate All are soluble

Chloride All are soluble except PbCl2

AgCl and HgCl.

Sulphate All are soluble except PbSO4, CaSO4 and BaSO4

Carbonate salts All are insoluble except Na2CO3

(NH4)2CO3, ammonium carbonateK2CO3

NAK

PAH

PantaiCahaya Bulan

NAK

Type Of Salts

Soluble saltInsoluble salt

Salt that undissolve in water (at room temperature)

We must know whether the salt is

Soluble

or

Insoluble

Salt that dissolve in water

(at room temperature)

Before preparing salt:

Have different method to prepare salt

Soluble salts

•Sodium salts•Potassium salts•Ammonium salts

Preparation of soluble salts

Acid + alkali salt + waterExample: HCl + NaOH NaCl + H2O

Other saltsAcid + metal oxide salt + waterExample: CuO + H2SO4 MgSO4 + H2OAcid + metal salt +

hydrogen gasExample: Mg + H2SO4 MgSO4 + H2

Acid + metal carbonate salt + water + carbon dioxideExample: CaCO3 + 2HNO3 Ca(NO3)2 + H2O + CO2

HCl + NaOH NaCl

Titration method

Evaporation/Heating

Cooling/crystallization

Filtration

Dry

T-TitrationH- Heat

C- Cooling/Crystallisation

F- FiltrationD- Dry

Three Hot Cats

Frighten Dog.!!

How to remember ? ? ?

Zn + 2HCl ZnCl2 + H2

Add metallic oxide/metal/carbonate oxide

Heating

Filtration

Recrystallisation

A- Adding (Dissolve)

H- Heating

F- Filtration

R- Recrystallisation

Amazing Hat feels

rocks..!

How to remember ? ? ?

PURIFICATION OF SOLUBLE SALT

Impure Salt Dissolved in distilled water

Dilute solution + impurities

Heat and evoporate to get saturated solution + impurities

Saturated solution + impurities

Cool it. Crystallisation process begins

Pure crystals formed. Filter

crystal out.

PHYSICAL CARACTERISTICS OF CRYSTALS

NaCl

CuSO4

FeSO4

K2Cr2O7

KMnO4

Fixed geometrical shapes

Flat surface, straight edges and sharp angles.

Fixed angles between two adjacent surfaces.

Same substance have same shapes but different sizes