Answer
the ration of Os atoms to O atoms is 1:4 , therefore the empirical formula of the component is $OsO_{4}$.
Work Step by Step
Strategy: 1- Convert the masses to moles 2- Divide each mole number by the smallest one in order to find the smallest integers.
The sample contains 2.16 g osmium (Os) and (2.89-2.16) = 0.73 g oxygen. Converted to moles we will have:
Moles of Os: 2.16g$\times\frac{1 mol(Os)}{190 g (Os)}$ = 0.01137 mol Os
Moles of oxygen: 0.73g$\times\frac{1 mol (O)}{16.0 g (O) }$ = 0.045625 mol O
The smallest mole number is the one of Os. Divide by this smallest number:
0.01137$\div$0.01137 = 1
0.045625$\div$0.01137 = 4.01 we can round this to 4 ( within experimental error)
So the ration of Os atoms to O atoms is 1:4 , therefore the empirical formula of the component is $OsO_{4}$
