The molar mass of potassium chloride is 74.55 g/mol. Potassium has molar mass 39.10 g/mol and chlorine has molar mass 35.45 g/mol. The potassium cation has one proton and the chloride anion has one electron, giving potassium chloride the chemical formula KCl.
The molar masses of the cation and anion are found by multiplying the number of atoms present of that element by the atomic mass of the element. Since both the cation potassium and the anion chloride have only one molecule each in the chemical formula, both their molar masses are simply added together to get the total molar mass of potassium chloride.