Answer
The empirical formula for Adrenaline is $C_{8}H_{11}O_{3}N$.
Work Step by Step
the first step is to assume we have 100 grams of adrenaline and thus we would have:
56.79 grams of carbon which is nearly 4.7325 moles of carbon.$(56.79 grams / 12 g/mol) = 4.7325$
6.56 grams of hydrogen which is 6.56 moles of hydrogen. $(6.56 grams / 1.0 g/mol) = 6.56 moles of hydrogen $
28.37 grams of oxygen which is nearly $(28.37 g / 16 g/mol) = 1.77 moles of oxygen $
and finally, 8.28 grams of nitrogen which is $(8.28 g / 14 g/mol) = 0.59 moles of nitrogen $
since the empirical formula is by definition the simplest ratio of moles of different atoms in a compound. We would divide by the smallest number of moles (here is nitrogen = 0.59 ) to get whole numbers or integers.
dividing each of the above by 0.59 would give:
8 moles of carbon
11 moles of hydrogen
3 moles of oxygen
and any number by himself is just 1, just like nitrogen moles here.
reconstructing the formula would give the empirical formula for Adrenaline is $C_{8}H_{11}O_{3}N$.
