d) Relative Formula Masses and Molar Volumes of Gases ​

1.16 Calculate Relative Formula Masses (Mr) from Relative Atomic Masses (Ar) ​

The total mass of the molecule calculated from the relative atomic masses of the atoms present in the compound is called relative formula mass.

Example:

• $H_2O = (1 \times 2) + 16 = 18$
• $(NH_4)_2CO_3 = ((2 + 1) \times 4) \times 2 + 12 + (16 \times 3) = 96$

1.17 Understand the Use of the Term Mole to Represent the Amount of Substance ​

A mole is a certain amount of substance. It is a general term to describe an amount of atoms, ions, or molecules.

1.18 Understand the Term Mole as the Avogadro Number of Particles (Atoms, Molecules, Formulae, Ions or Electrons) in a Substance ​

A mole is defined as the amount of substance which contains the Avogadro number of particles.

Avogadro Number = $6 \times 10^{23}$

1.19 Carry Out Mole Calculations Using Relative Atomic Mass (Ar) and Relative Formula Mass (Mr) ​

Mole = Number of Particles / $6 \times 10^{23}$

1.20 Understand the Term Molar Volume of a Gas and Use Its Values (24 dm3 and 24,000 cm3) at Room Temperature and Pressure (rtp) in Calculations ​

Volume of one mole of any gas is molar volume. It is 24dm3 or 24000 cm3 at R.T.P.