The two isotopes of potassium with significant abundance in nature are ³⁹K (isotopic mass 38.9637 amu, 93.258%) and ⁴¹K (isotopic mass 40.9618 amu, 6.730%). Fluorine has only one naturally occurring isotope, ¹⁹F (isotopic mass 18.9984 amu). Calculate the formula mass of potassium fluoride.
