☰
Atoms And Molecules
Define mole and Avogadro's number? Will the weight of 1 mole of sodium and 1 mole of oxygen be the same?
Mole: Mole is the measurement in chemistry. It is used to express the amount of a chemical substance.
One mole is defined as the amount of substance of a system which contains as many entities like, atoms, molecules, and ions as there are atoms in 12 grams of carbon - 12'.
Avogadro number: The number of the particles present in one mole of any substance is equal to 6.022x1023. This is called Avogadro's number or Avogadro's constant.
1 mole of sodium (6.023 x 1023 atoms) weighs 23 g (atomic mass). And 1 mole of oxygen (6.023 x 1023 molecules) weighs 32 g (molecular mass). Thus, particles present in 1 mole of oxygen and sodium is same such as (6.023 x 1023 atoms) but the weight could not be same.
Sponsor Area
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.
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 ?
Sponsor Area
Sponsor Area