Given a compound with a composition of 15.66% A and 84.34% Z by mass, what is the empirical formula of this compound?

Question

Three elements, A, Q, and Z, have the molar masses indicated in the table below. Given a compound with a composition of 15.66% A and 84.34% Z by mass, what is the empirical formula of this compound? Remember to enter subscripts as normal numbers (ie H₂O is entered as H2O) and to enter elements in the same order they were given.

element symbol	molar mass
A	15.45 g/mol
Q	20.05 g/mol
Z	41.62 g/mol

thank you in advance!

Answer 1

Let's assume we have 100 grams of this mystery substance, therefore we have 15.66 g A and 84.34 g Z.

first we convert grams to moles:

15.66 g A X (1 mol/15.45 g) =1.01 mol

84.34 g Z X (1 mol/41.62 g)=2.02 mole

therefore the empirical formula is AZ2