Oxides of Magnesium and Calcium

Oxides of Mg, Ca 

MgO (Magnesia)

It is made by heating magnesite (MgCO3).

MgCO3  MgO + CO2

It is very slightly soluble in water imparting an alkaline reaction to the solution.

MgO + H2O → Mg(OH)2

Calcium oxide, Quick lime CaO 


It is prepared by heating limestone in a rotatory kiln at 1070 – 1270 K.

CaCO3 1070-1270k CaO + CO2; ΔH = + 179.9 KJ       

The temperature should not be raised above 1270 K. Otherwise silica present as impurity in lime will combine with calcium oxide to form infusible calcium silicate.

            above 1270k

CaO + SiO2 ———→ CaSiO3         

(i)     It is a white amorphous solid with m.p. of 2870 K.

(ii)    When exposed to atmosphere, it absorbs moisture and CO2 forming slaked lime and calcium carbonate respectively.

CaO + H2O (Moisture)  Ca(OH)2

CaO + CO2  CaCO3

(iii) On adding water, it produces a hissing sound a large amount of heat is evolved which converts water into steam. This process is called slaking of lime and the fine powder obtained is called slaked lime.

CaO + H2O  Ca(OH)2 ; ΔH = -63KJ

(iv)   Action of acids and acidic oxides

It is a basic oxide and hence combines with acids and acidic oxides forming salts.

CaO + 2HCl  CaCl2 + H2O

CaO + SO2  CaSO3 

(v)    Reaction with coke

When heated with coke in electric furnace at 2273 – 3273 K, it forms calcium carbide.

CaO + 3C ————→ CaC2 + Co       

(vi)   Reaction with ammonium salt

On heating with ammonia salts, it liberates ammonia gas.

CaO + 2NH4Cl  CaCl2 + 2NH3 + H2O

(i) It is used as a building materials.

(ii)It is used for drying alcohols and non acidic gases.

(iii)It is used in the preparation of ammonia and soda lime (CaO + NaOH).

(iv)It is used as a basic lining in furnaces.

Why does a piece of burning magnesium continue to burn in SO2?


This is because the reaction of Mg with SO2 is exothermic.

2Mg + SO2 —→ 2MgO + 1/8S8 + Heat


Name the substance used for drying alcohol and non-acidic gases.

To know more about the study material of engineering and medical exams, please fill up the form given below:

We promise that your information will be our little secret. To know more please see our Privacy Policy
We promise that your information will be our little secret. To know more please see our Privacy Policy


Sign Up with Facebook

Signing up with Facebook allows you to connect with friends and classmates already using askIItians. It’s an easier way as well. “Relax, we won’t flood your facebook news feed!”

Related Resources
Difference-Alkaline Earth Metals and Alkali Metals

Difference between alkaline earth metals and...

Properties of Lithium

Properties of Lithium (a) Physical Properties (i)...

Anomolous Behaviour of Lithium

Anomolous Behaviour of Lithium and its Diagonal...

Halides of Alkali Metals

Halides of Alkali metals:- The alkali metals...

Alkaline Earth Metals

Alkaline Earth Metals The group 2 of the periodic...

Chemical Properties of Group II Elements

Chemical Properties of Group – II elements...

Magnesium Sulphate

Magnesium Sulphate Magnesium sulphate, Epsom salt...

Physical Properties of Alkali Metals

PHYSICAL PROPERTIES (i) All the alkali elements...

Properties of Sodium

Properties of Lithium (a) Physical Properties (i)...

Carbonates and Bicarbonates of Magnesium and Calcium

Calcium Carbonate (CaCO 3 ) It occurs in nature as...

Solved Examples on Alkali Metals

Illustration: What is the most reactive alkali...

Salts of Oxoacids

Salts of oxoacids Since the alkali metals are...

Anamolous Behaviour of Beryllium

Anamolous Behaviour of Beryllium The properties of...

Plaster of Paris

Plaster of paris, CaSO 4 .1/2 H 2 O or (CaSO 4 ) 2...

Occurrence and uses of Alkaline Earth Metals

Occurrence and uses of alkaline earth metals...

Compounds of Alkaline Earth Metals

Halides The alkaline earth metals combine directly...

Physical Properties of Alkaline Earth Metals

Physical Properties of Alkaline Earth Metals...

Chemical Properties of Alkaline Earth Metals

Reaction with hydrogen – (Formation of...

Minerals of Lithium

Minerals of Lithium Difficulties encountered...

Some other Compounds of Alkali Metals

Bicarbonates of Metals (Na, K) Sodium Bicarbonate...

Properties of Magnesium

Properties of Magnesium Physical Properties (i)...

Physical Characteristics of Alkaline Earth Metals

Melting and boiling points The alkaline earth...

Hydroxides of Alkali Metals

Hydroxides of Metals (Na, K) Sodium Hydroxide...

Carbonates of Alkali Metals

Carbonates of Metals (Na, K) Sodium Carbonate...

Chemical Properties of Alkali Metals

CHEMICAL PROPERTIES The alkali metals are highly...


Magnesium Metal Magnesium occurs as magnesite MgCO...

Introduction of S and P Block Elements

INTRODUCTION The elements in the long form of the...

Oxides of Alkali Metals

Oxides of Alkali Metal Oxides of Sodium: The...

Characteristics of Alkaline Earth Metal Compounds

General characteristics of compounds of the...

Hydroxides of Magnesium and Calcium

Hydroxides of Mg & Ca Magnesium Hydroxide...