One mole of any element or chemical compound is always the same number. One mole of hydrogen would mean there are 6.022 × 10 23 atoms of hydrogen. Molarity is also considered molar concentration because it is the measure of a concentration of a solution. Molarity is the number of moles of solute per litre of solution.
Number of moles = Mass of substance / Mass of one mole
Example: How many moles of sodium chloride is present in a sample that has a mass of 1.17g ?
The molar mass of Sodium Chloride = 2 3 + 3 5.5 = 5 8.5 g
No. of moles = Mass of NaCl / Molar mass of NaCl
= 1.17 /58.5
= 0.0 2 moles