Respuesta :
We first set about determining the empirical formula of the compound. From the principle of mass conservation, we can assume that the empirical compound contains 4.04 g of N and 11.46 g of O.
We now convert the mass of each element into the number of moles by dividing by the molar mass.
(4.04 g N)/(14.0067 g/mol) = 0.2884 mol N
(11.46 g O)/(15.999 g/mol) = 0.7163 mol O.
To find the empirical formula, we divide each molar quantity by the smaller of the two. That would be the number of moles of nitrogen.
(0.2884)/(0.2884) = 1
(0.7164)/(0.2884) = 2.48 ā 2.5.
To make both whole numbers, we multiply each numeral by 2:
(1)(2) = 2
(2.5)(2) = 5.
So, the empirical formula of our compound is NāOā .
To find the molecular formula of our compound, we must find the factor by which the molar mass of the actual compound differs from the molar mass of the empirical compound. The molar mass of the empirical compound, NāOā , is 108.01 g/mol. We are told that the molar mass of the actual compound is 216.0 g/mol. So, the two differ by a factor of (216.0 g/mol)/(108.01 g/mol) = 1.99 ā 2.
The molecular formula of this compound is thus NāāāOā āā or NāOāā.
