Answer:
CH₄N₂O
Explanation:
Let's assume 100 g of the compound, thus, the mass of each substance is it percent multiplied by 100:
C = 20.0 g (20% = 0.20, and 0.20*100 = 20.0)
H = 6.7 g
N = 46.6 g
O = 100 - (20+6.7+46.6) = 26.7 g
The number of moles of each compound is the mass divided by the molar mass. The molar masses are C = 12.011 g/mol, H = 1.00794 g/mol, N = 14.01 g/mol, and O = 15.999 g/mol, so:
nC = 20/12.011 = 1.67 mol
nH = 6.7/1.00794 = 6.65 mol
nN = 46.6/14.01 = 3.33 mol
nO = 26.7/15.999 = 1.67 mol
The empirical formula is the formula with the minimum possible number of the moles of each compound, which must be proportional to the percent of each one. So, we must divide each number of moles for the smallest, 1.67:
C = 1.67/1.67 = 1
H = 6.65/1.67 = 4
N = 3.33/1.67 = 2
O = 1.67/1.67 = 1
So, the empirical formula is CH₄N₂O.
