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Atoms And Molecules
Carbon and oxygen combine in two different ways to form carbon dioxide and carbon monoxide. In carbon monoxide, 12 g carbon combines with 16 g oxygen. In carbon dioxide 12 g carbon combines with 32 g oxygen. Which law of combination is illustrated by this experiment? Explain.
The above experiment illustrates law of multiple proportions. 16 g and 32 g of oxygen respectively are required to combine with a fixed weight, i.e., 12 g of carbon to form carbon monoxide and carbon dioxide. The ratio of oxygen which combines with a fixed weight of carbon is 16 : 32 or 1 : 2, a simple whole number. This is law of multiple proportions.
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When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen ? Which law of chemical combination will govern your answer?
What are polyatomic ions? Give examples.
(a) Magnesium chloride
(b) Calcium oxide
(c) Copper nitrate
(d) Aluminium chloride
(e) Calcium carbonate
Give the names of the elements in the following compounds.
(a) Quick lime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate.
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.
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