Calculate the molar mass of the following:
(i) H2O (ii) CO2 (iii) CH4
(i) H2O
Atomic Mass of Hydrogen = 1g
Atomic Mass of Oxygen = 16g
From the molecular formula of water, it is understood that in 1 mole of water, 2 moles of hydrogen and 1 mole of oxygen is present.
So Molecular Mass of Water = [2×1] + [16×1]
= 2 + 16
= 18g
Therefore, the molecular mass of water is 18g
(ii) CO2
Atomic Mass of Carbon = 12g
Atomic Mass of Oxygen = 16g
From the molecular formula of carbon dioxide, it is understood that in 1 mole of carbon dioxide, 1 mole of carbon and 2 moles of oxygen is present.
So Molecular Mass of Carbon Dioxide = [12×1] + [16×2]
= 12 + 32
= 44g
Therefore, the molecular mass of carbon dioxide is 44g
(iii) CH4
Atomic Mass of Carbon = 12g
Atomic Mass of Hydrogen = 1g
From the molecular formula of methane, it is understood that in 1 mole of methane, 1 mole of carbon and 4 moles of hydrogen is present.
So Molecular Mass of Methane = [12×1] + [4×1]
= 12 + 4
= 16g
Therefore, the molecular mass of methane is 16g