Chemical Equations and Reactions

Question 1

Calcium Oxide reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.

Answer 1

CaO(s) + H2O(l) —– Ca(OH)2(aq) + Heat
(Quick Lime) (Slaked Lime)
Combination Reaction

Question 2

Whitewash Reaction?

Answer 2

Calcium Hydroxide reacts slowly with Carbon Dioxide in air to form a thin layer of Calcium Carbonate on the walls. Calcium Carbonate is formed after two or three days of whitewashing and gives a shiny finish to the walls. Chemical Formula of Marble is also CaCO3.
Ca(OH)2(s) + CO2(g) ———— CaCO3(s) + H2O(l).
(Calcium Hydroxide) (Calcium Carbonate)

Question 3

Chemical Reaction of Marble?

Answer 3

CaCO3

Calcium Carbonate

Question 4

Burning of Coal?

Answer 4

C(s) + O2(g)—————- CO2

This is an exothermic Reaction.

Question 5

Formation of water from H2(g) and O2(g)?

Answer 5

2H2(g)+O2(g)————-2H2O(l)

Question 6

Exothermic Reactions?

Answer 6

Reactions in which heat is released along with the formation of products is called Exothermic Reactions.
Examples-
Burning of Natural Gas
CH4(g) + 2O2(g)——————- CO2(g) + 2H2O
Respiration
C6H12O6(aq) + 6O2(aq)———– 6CO2(aq) + 6H20(l)+ energy
The decomposition of vegetable matter into compost is also an example of an exothermic reaction.

Question 7

Ferrous sulphate crystals (FeSO4 ,7H2O) lose water when heated and the colour of the crystals changes. It then decomposes to ferric oxide (Fe2O3) , sulphur dioxide (SO2) and Sulphur trioxide (SO3). Ferric Oxide is a solid while SO2 and SO3 are gases.

Answer 7

2FeSO4(s)—-(Heat)——- Fe2O3(s)+So2(g) + SO3(g)
(Ferrous Sulphate) (Ferric Oxide)

Decomposition Reaction

Question 8

Decomposition of Calcium Carbonate to Calcium Oxide and Carbon Dioxide on heating is an important decomposition reaction used in various industries.

Calcium Oxide is called?
One of the manufacturer of?

Answer 8

CaCO3(s)——Heat——- CaO(s)+CO2(g)
(Limestone) (Quick Lime)

Decomposition Reaction
Lime or Quick Lime
Cement

Question 9

When a thermal decomposition reaction is carried out by heating,it is called?

Answer 9

Thermal Decomposition Reaction

Question 10

Lead Nitrate

Answer 10

Colourless

Question 11

Lead Oxide

Answer 11

Yellow

Question 12

Nitrogen Dioxide

Answer 12

Brown fumes

Question 13

Why does white silver chloride turns grey in sunlight?

Answer 13

White Silver Chloride turns grey due to the decomposition of Silver Chloride into Silver and Chlorine by light.
2AgCl(s)—————Sunlight——————- 2Ag(s)+Cl2(g)

Question 14

Which reaction is used in photography?

Answer 14

2AgBr(s)———-Sunlight———2Ag(s)+Br2(g)

Silver Bromide

Question 15

Displacement reaction-
Fe(s)+CuSo4(aq)———– FeSO4(aq) + Cu(s)
Copper Sulphate Iron Sulphate

Answer 15

Displacement reaction-
Fe(s)+CuSo4(aq)———– FeSO4(aq) + Cu(s)
Copper Sulphate Iron Sulphate

Question 16

Displacement reaction 2-
Zn+CuSO4(aq)————- ZnSO4(aq)+Cu(s)
Copper Sulphate Zinc Sulphate

Answer 16

Displacement reaction 2-
Zn+CuSO4(aq)————- ZnSO4(aq)+Cu(s)
Copper Sulphate Zinc Sulphate

Question 17

Displacement reaction 3-
Pb(s)+CuCl2(aq)———– PbCl2(aq) + Cu(s)
Copper Chloride Lead Chloride

Answer 17

Displacement reaction 3-
Pb(s)+CuCl2(aq)———– PbCl2(aq) + Cu(s)
Copper Chloride Lead Chloride

Question 18

Precipitate Reaction ?

Answer 18

Any reaction that produces a precipitate can be called a precipitation reaction.
Na2So4(aq)+ BaCl2(aq)——-BaSO4(s)+NaCl(aq)
Sodium Sulphate Barium Chloride Barium Sulphate Sodium Chloride

Question 19

Double Displacement Reactions

Answer 19

Reactions in which there is an exchange of ions between the reactants are called double displacement reactions.