Quantitative Chemistry and Energetics
A mole is a measure of the amount of substance. One mole contains 6 x 1023 (also known as the Avogadro Number) particles (atoms, molecules or formulae) of the substance. For example, 1 mol of sodium contains 6 x 1023 atoms of sodium.
Calculating Relative Atomic Mass
Chlorine has two isotopes: chlorine-35 and chlorine-37. A typical sample will be 75% chlorine-35 and 25% chlorine-37.
The RAM = (0.75 x 35) + (0.25 x 37) = 35.5g