we have to first find the empirical formula. Empirical formula gives the simplest ratio of whole number of components in a compound.
oxygen phosphorous
mass 56.36 g 43.64 g
number of moles 56.36 g/ 16 g/mol 43.64 g/ 31 g/mol
=3.5 = 1.4
divide by least number of moles
3.5/1.4 = 2.5 1.4/1.4 = 1
multiply by 2 to get a whole number
O - 2.5 x 2 = 5
P - 1x2 = 2
Therefore empirical formula - P₂O₅
Mass of one empirical unit - 31x2 + 16 x 5 = 62 + 80 = 142
number of empirical units - 283.9 / 142 = 2
Therefore molecular formula - 2(P₂O₅)
molecular formula - P₄O₁₀
