In
lesson 2 you have learnt how to write and balance chemical
equations. Stoichiometry deals with the proportions in
which elements or compounds react with one another.
In this section we shall learn how to use the stoichiometric
information in a balanced chemical equation for making some
calculations.
Significance
of balancad chemical equation
Balanced
chemical equation carries the following information:
a)
Qualitative information carried by a balanced chemical equation
•
Reactants taking part in the reaction
• Products formed in the reaction
• Physical states of different reactants and products
(if given)
b)
Quantitative information carried by a balanced chemical
equation
•
Number of molecules of different reactants and products
taking part in the reaction
• Number of moles of different reactants and products
taking part in the reaction
• Masses of different reactants and products taking
part in the reaction
• Relationship between moles of different reactants
and products taking part in the reaction
• Relationship between masses of different reactants
and products taking part in the reaction
• Relationship between volumes of different gaseous
reactants and products taking part in the reaction
Let
us understand how to get this information from a chemical
equation with the help of an example.
Information
carried by a chemical equation
| |
2Na(s) |
+ |
2H2O(l) |
—> |
2NaOH(aq) |
+ |
H2(g) |
| Name |
sodium |
|
water |
|
sodium hydroxide |
|
hydrogen |
| Physical states |
solid |
|
liquid |
|
aqueous solution |
|
gas |
| Moles |
2 moles |
|
2 moles |
|
2 moles |
|
1 mole |
| (molar masses) |
(Na=23) |
|
(H2O=2+16=18) |
|
(NaOH=23+16+1=40) |
|
(H2= 2) |
| Masses |
2*23=46g 1*2=2g
|
|
2*18=36g |
|
|
|
2*40=80g |
| Volume of L=22.7L gaseous substance |
|
|
|
|
|
|
1*22.7 |
