The mass ratio of Kr to F in a particular compound is 2.206:1. How many grams of fluorine are present if the compound contains 713.3 grams of Kr?
it's a proportion problem.
2.206 g Kr /1 g F = 713.3 g Kr/ (x g F)
cross multiply and solve for x
2.206 g Kr /1 g F = 713.3 g Kr/ (x g F)
cross multiply and solve for x