Suppose you know that a compound is 11.2% H and 88.8% O. What information do you need to determine the empiric

Answer 1

suppose the compound has the formula On Hm in that case the ratio of their masses in the formula would be On/Hm = 16*n/1*m

On/Hm = 16n/m

if you calculate the ratio 88.8/11.2 =7.92 not very far from 8

this means that 16n/m =8 or n/m =1/2

that it exists 1 atom oxygen for 2atoms hydrogen

the compound is water H2O

Answer 2

by assuming that mass of the compound = 100g.
convert, the % into masses of each element.
that is, in 100g of the compound, you have 11.2g of H and 88.8g of O. then, find out the no. of moles of each element.
no.of moles of H = 11.2g/1 = 11.2 moles
no.of moles of O = 88.8g/16 = 5.55 moles (= 6 moles approx.)
relative no.of moles of H = 11.2/11.2 = 1 mole
relative no.of moles of O = 5.55/11.2 = 0.49 moles (=0.5 moles approx.)
therefore empirical formula of the compound containing H and O only is HO1/2.
if the molecular mass of the compound is known, then we can also calculate the actual molecular formula, by
letting,
(molecular mass of H + 5*molecular mass of O) n = molecular mass of compound, then calculate n, and we know the molecular formula.