Answer is: empirical formula is HNO₃.
m(unknown compound) = 8,5 g.
m(N₂O₅) = 7,29 g.
m(H₂O) = 1,21 g.
n(N₂O₅) = m(N₂O₅) ÷ M(N₂O₅).
n(N₂O₅) = 7,29 g ÷ 108,01 g/mol.
n(N₂O₅) = 0,0674 mol.
n(H₂O) = m(H₂O) ÷ M(H₂O).
n(H₂O) = 1,21 g ÷ 18 g/mol.
n(H₂O) = 0,0673 mol.
n(H₂O) : n(N₂O₅) = 0,0673 mol : 0,0674 mol.
n(H₂O) : n(N₂O₅) = 1 : 1.
Compound has two hydroge, two nitrogen and six oxygen, can divided with two.
