Law of Chemical Combination
Einstein derived an expression to the inter conservation of matter and energy given by E= mc2, where c is the velocity of light, E is energy and M is the mass.
The theory has now been put in the form of a law called the law of conservation of mass or law or law of indestructibility of matter
Law of conservation of mass state that matter can neither be created nor destroyed in the course of any chemical reaction.
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The Law of Definite Proportion or Constant Composition
The Law of Definite Proportion or Constant Composition state that all pure samples of the same chemical compound contain the same elements combined in the same proportion by mass.
The Law of Multiple Proportion
The law of multiple proportion state that if two element A and B are combined together to form more than one compound, the several masses of A which is separately combined with a fix masses of B are in the same sample ratio.
Some given solution to some test questions
1. What is the amount (in mole) of sodium trioxocarbonate (iv) in 5.3g of the compound? ( Na2Co3 = 106g)
Mole = Reacting Mass/molar mass
Mole = 5.3/106 = 0.05mole
2. In two separate experiments, 0.36 and 0.71g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20g and 0.40g of respectively. The data above represents the law of
A. Multiple proportion Answer
B. conservation of mass
C. constant proportion
D. reciprocal proportion
3. Calculate the percentage composition of water of crystalization in the compound below? Sodium trioxocarbonate (iv) decahydrate i.e Na2CO3.10H20
A. 62.94% Answer
2 x 23 + 1 x 12 + 3 x 16 + [20 x 1 + 10 x 16]
46 + 12 + 48 + 20 + 160 = 286g
[20 x 1 + 10 x 16] water of crystallization is 180
Then 180/286 x 100 = 62.94%
Try this and solve
6g of metal M reacts completely with 23.66g of chlorine to form 29.66g of the metallic chloride.find the emperical formula of the metallic chloride. ( M=27, Cl=35.5)
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