Some solved example questions on the mole concept are provided in this subsection.
Q.1: How many moles of iron are present in a pure sample weighing 558.45 grams?
A.1: The molar mass of iron is 55.845 g/mol. Therefore, the number of moles of iron in the pure sample weighing 558.45 grams is:
= 10 moles.
Q.2: How many molecules of water are present in 36 grams of water?
A.2: The molar mass of water is 18 (approximately). Therefore, 36 grams of water makes up a total of 2 moles. Each mole has 6.022*1023 water molecules. The total number of H2O molecules in 36 grams of water is: 12.044*1023
Q.3: How many grams of carbon can be found in 1 mole of carbon dioxide?
A.3: 1 mole of CO2 contains 1 mole of carbon and 2 moles of oxygen. The molar mass of carbon is 12.0107 g/mol. Therefore, 1 mole of CO2 contains 12.01 grams of carbon and 32 grams of oxygen.