Chemistry CCEA AS Level 2.1 (Formulae and amounts of a substance)

What is an empirical formula?

A formula which shows the simplest whole number ratio of atoms in each element of a compound

What is a molecular formula?

A formula which shows the actual number of atoms of each element in a molecule

How do you calculate empirical formula?

1. List the species and their amounts

2. Convert amounts to moles

3. Divide though by smallest value

4. Scale up to simplest whole number ratio

How do you calculate molecular formula?

1. Calculate Mr of empirical formula

2. Divide Mr of molecule by Mr of empirical formula and convert to nearest whole number

3. Multiple empirical formula by number

What is molar gas volume?

The volume of one mole of gas under specified temperature and pressure (e.g - 24dm^3 at 20°C and one atmospheric pressure)

How is moles calculated from gas volume?

Moles= gas volume (dm^3)/molar gas volume (dm^3)

How is percentage yield calculated?

Percentage yield = Actual yield/Theoretical yield x 100

How is atom economy calculated?

Atom economy = mass of desired product/total mass x 100