Mole concept

Measuring matter

• A mass

• A volume

• A count

Count

• One dozen = 12

• One mole = Avogadro’s number of items

• Avogadro’s number = 6.022 x 10²³

Molar Mass – the mass of one mole of a substance

Determine the molar mass of the following substances.

1. Carbon C = 12.011 g/mol

2. Iron Fe = 55.847 g/mol

Converting between moles and mass.

Example: What is the mass of 5.00 mol of water?

Mass = (moles)(molar mass)

= (5.00 mol)(18.105 28 g/mol) = 90.0764

= 90.1 g/mol )

Molar Volume

• The volume occupied by one mole of a gas at STP

• STP = standard temperature and pressure

• STP = 0ºC and 101.3 kPa

• The molar volume of any gas at STP is 22.4 L/mol

Example: What is the volume of 3.00 mol of carbon dioxide at STP?

Volume = (moles)(molar volume)

= (3.00 mol)(22.4 L/mol)

= 67.2 L )