Question

how many grams of F are there in a 36.01 g sample of CrF3 given that 18.83 g of this sample are Cr?

Answer 1

Ca = 40.1  

2 F = 38.0  

--------------  

78.1  

% F = 38.0/78.1  

Now you can calculate mass of F  

0.487 ( 255 g ) = 124 g F