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Atoms And Molecules
Hydrogen and oxygen combine in two different ways to produce water and hydrogen peroxide. Which of Dalton’s law does this observation confirm? Explain.
In water 1 g of hydrogen combines with 8 g of oxygen. And in hydrogen peroxide, 2 g of hydrogen combines with 16 g of oxygen. The ratio of oxygen in water and hydrogen peroxide combining with the same amount of hydrogen i.e., 1 g is 8 : 16 or 1 : 2—a small integral ratio. This is law of multiple proportions which defines as under.
When two elements combine to form more than one compound, the masses of one element that combine with a given mass of the other element in different compounds are in the ratio of small whole numbers.
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Calculate the molar mass of the following substances:
(a) Ethylene
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3.
What is the mass of:
(a) 1 mole of nitrogen atoms
(b) 4 moles of aluminium atoms
(c) 10 moles of sodium sulphite.
Convert into mole
(a) 12 gm of oxygen gas
(b) 20 gm of water
(c) 22 gm of carbon dioxide.
What is the mass of?
(a) 0.2 mole oxygen atoms.
(b) 0.5 mole of water molecules.
Calculate the number of molecules of sulphur (S8) present in 16 gm of solid sulphur.
Calculate the number of aluminium ions present in 0.56 gm of aluminium oxide.
Explain law of conservation of mass.
50 g of 10% lead nitrate is mixed with 50 g of 10% sodium chloride in a closed vessel. After the reaction has taken place, it was found that 6.83 g of lead chloride was precipitated. Besides, the reaction mixture contained 90 g water and sodium nitrate. Calculate the amount of sodium nitrate formed.
Name and explain two important laws of chemical combination ?
What are the postulates of Dalton’s atomic theory of matter?
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