Atoms And Molecules
Define the term gram atom. How is it related to the mole and Avogadro number?
Gram atom or Gram atomic mass. The atomic mass of an element expressed in grams is called gram atomic mass or gram atom.
1 gram atom of any element contains 6.023 x 1023 (Avogadro number) atoms of the
element. It is equal to 1 mole of atoms.
1 gram atomic mass = 6.023 x 1023 atoms = 1 mole.
(Avogadro number)
The gram atomic mass of an element is equal to the masses of its 6.023 x 1023 atoms. Examples. One gram atom of hydrogen atom weighs one gram and contains 6.023 x 1023 hydrogen atoms. 1 mole of hydrogen atom also weighs 1 gram.
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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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