Page 57 - Science Class 07

Compound Formula Elements and Their Atoms

Carbon Dioxide CO Carbon (1), Oxygen (2)
2
Sulphuric Acid H SO Hydrogen (2), Sulphur (1), Oxygen (4)
2
4
Potassium Permanganate KMnO Potassium (1), Manganese (1), Oxygen (4)
4
Nitric Acid HNO Hydrogen (1), Nitrogen (1), Oxygen (3)
3
Ammonia NH Nitrogen (1), Hydrogen (3)
3
Hydrochloric Acid HCL Hydrogen (1), Chlorine (1)
Aluminum Bromine AIBr Aluminum (1), Bromine (3)
3
Phosphorous Pentoxide P O Phosphours (2), Oxygen (5)
2 5
Borax Na B O Sodium (2), Boron (4), Oxygen (7)
2 4 7
Sugar C H O Carbon (12), Hydrogen (22), Oxygen (11)
12 22 11
Copper Sulphate CuSO Copper (1), Sulpher (1), Oxygen (4)
4
Carbonic Acid H CO Hydrogen (2), Carbon (1), Oxygen (3)
2 3
Sodium Hydroxide NaOH Sodium (1), Oxygen (1), Hydrogen (1)
Ammonium Chloride NH Cl Nitrogen (1), Hydrogen (4), Chlorine (1)
4

CHEMICAL EQUATIONS HOW TO BALANCE AN EQUATION?

A chemical equa on is just a chemical reac on, Let us take the unbalanced equa on:
but it is expressed using chemical symbols and H + O H O
2
2
2
formulae.
v Atoms of hydrogen are equal on both sides.
How to write correct chemical equa on? i.e. they are 2.
v The chemical formulae of reactant v But atoms of oxygen are unequal. On the
(elements or compounds) are wri en on le side they are 2, but on the right side it
the le hand side with plus (+) sign to is only 1.
dis nguish each par cipa ng reactants.
v So, to make them equal, we shall mul ply
Mg + O
2 the right hand side by 2. Thus, the equa on
v An arrow (Ý) is placed just a er ending will become:
posi on of reactants. The arrow means H + O 2H O
“yield to”. 2 2 2
v Now, the atoms of hydrogen have become
Mg + O 2 unequal. So, we shall mul ply H by 2 to
2
v To the right side of the arrow we write the make the equa on balanced as:
chemical formulae of the product. 2H + O 2H O
2 2 2
Mg + O 2 2MgO Similarly, to balance the equa on
v Finally, we balance, the equa on. Mg + O 2MgO
2
2Mg + O 2MgO
2

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