C2 - Calculations Notes

Chemistry Calculations:

Ar:

Usually the same as Relative Atomic Mass of an element (bigger numbers on periodic table.

Mr:

Sum of all the Relative Atomic Masses.

Eg. MgCl2

24 + (35.5 x 2) = 95

Empirical Formulae:

1) List all elements in compound

2) Write experimental masses/percentages.

3) Divide masses/percentages by the Ar.

4) Turn the numbers into a ratio and cancel it down.

Eg.

Empirical formula of iron oxide produced when 44.8g of iron reacts with 19.2 of oxygen.

 Fe               O          …