Grade 10 ppt project

1. Dr. A.K. Gupta
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2. All the Chemical reactions take place according to the certain Laws.
These are called ‘Laws of Chemical combination”.
The various Laws of Chemical combination are :-
1. Law of Conservation of Mass.
2. Law of Multiple Proportions.
3. Law of Constant Composition.
4. Law of Reciprocal Proportions.
5. Gay Lussac’s law of Gaseous Volumes.
(Law of Combining Volumes)
The first Four laws are related to the mass relationships while the fifth one
Deals with the volume of the reacting gases.
Let us see what these Laws are.
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3. Given By : Antoine Lavoisier, in the year 1774.
In all Physical and Chemical changes, the total mass of
the reactants is equal to that of the products.
In other words …
Matter can neither be created nor destroyed.
Hence the Law is also called as The Law of indestructibility of Matter.
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4. To prove this Landlot took NaCl in one limb of Landlot’s tube, and AgNO3
in the other .
Then he mixed the two solutions by inverting the tube.
AgCl + NaNO3
NaCl AgNO3
NaCl + AgNO3 NaNO3 + AgCl
(23+35.5) +(108+14+48) (23+14+48) + (108+35.5)
228.5 = 228.5 4

5. Given by: John Dalton in the year 1804
When two elements combine to form two or more
chemical compounds, then the weights of one of the
elements which combines with a fixed weight of the
other, bear a simple ratio to one another.
For example Nitrogen and Oxygen combine with each
other to form following compounds:
N2O, NO, N2O3, N2O4, N2O5
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6. Compounds Nitrous Nitric Nitrogen Nitrogen Nitrogen
Oxide Oxide Trioxide Tetra oxide Pent oxide
Elements
Formula N2O NO N2O3 N2O4 N2O5
Wt. of 28 14 28 28 28
Nitrogen
Wt. of 16 16 48 64 80
Oxygen
When N is 14 14 14 14 14
taken 14
Then O is 8 16 24 32 40
The simple ratio of Oxygen which combines with fixed
amount of Nitrogen (14 in this example) is
1:2:3:4:5, which is a simple ratio.
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7. Given by: J.L. Proust in the year 1799.
A Chemical Compound is always found to be made up of
the same elements combined together in the same fixed
proportion by weight.
For example pure Carbon dioxide obtained from whatever source (Heating CaCO3
or burning carbon, or by reacting MgCO3 with HCl), will always be made up of
12 parts of Carbon and 32 parts of Oxygen by weight.
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8. Given by: Richter, in the year 1792.
The ratio of the weights of two elements A and B which
combine separately with a fixed weight of the third element
C is either the same, or some simple multiple, of the ratio
of the weights, in which A and B combine directly with
each other.
To understand this better, let us assume that A is Carbon, B is Oxygen,
and C is Hydrogen .
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9. Remember: A is Carbon, B is Oxygen, and C is Hydrogen.
Carbon and Oxygen combine with Hydrogen to form CH4 and
H2O respectively. In CH4, 4 gram H combine with 12 gram
Carbon, while in H2O, 2 gram Hydrogen combine with 16 gram
Oxygen or 4 gram H will combine with 32 gram O.
Thus the ratio of C:O which combine with 4 gram of H
is 12:32 or 3:8
Now C and O combine directly with each other to form CO2
and the ratio of their weights is 12:32 or 3:8, which is same as
that with Hydrogen.
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10. Ratio
4:12
H H H
H H H Ratio2:16
or 4:32
Ratio 12:32
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11. Given by: Gay Lussac in the year 1808.
When gases react together, they always do so in volumes
which bear a simple ratio to one another and to the
volumes of the products, provided all measurements of
volumes are done under similar conditions of temperature
and pressure.
Reactions Ratio
N2 + 3 H2 2 NH3 1:3:2
2 H2 + O2 2 H2O 2:1:2
H2 + Cl2 2 HCl 1:1:2
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12. A
Presentation
By
Dr. A.K. Gupta
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