1
Q
What is empirical formula?
A
The simplest whole number ratio of each type of atom in a compound.
2
Q
How do we work out empirical formula?
A
- Write the mass of each element
- Find the Ar of each element
- Find how many moles there are in each element by doing mass/Mr
- Find the smallest value of moles
- Divide each element by the smallest value of moles
3
Q
What would be the empirical formula of 2.45g of sulphuric acid with 0.05g hydrogen, 0.8g sulphur and 1.6g oxygen?
A
- H = 0.05g, S = 0.8g, O = 1.6g
- H = 1, S = 32, O = 16
- (Moles) H = 0.05, S = 0.025, O = 0.1
- S is the smallest
- (Dividing by S) H = 2, S = 1, O = 4
- Empirical formula = H2SO4
4
Q
How can we calculate % mass?
A
- (Mass of desired/mass of compound)X100
OR
- (Ar of element/Mr of compound) X100
5
Q
How do we calculate empirical formula from %?
A
Work in the same way but with 100g of the substance and follow the same steps as before.
