Reductic acid contains 79.25% carbon atoms by mass, 5.66% hydrogen atoms by mass, and 15.09% oxygen atoms by mass. Its simplest formula is the same as its molecular formula. The number of hydrogen atoms in a molecule of reductic acid is:
Taking a 100 g sample gives you the following:
79.25 g carbon, 5.66 g hydrogen and 15.09 g oxygen.
Convert to moles;; i.e., moles = grams/atomic mass.
moles C = 79.25/12 = 6.60
mols H = 5.66/1 = 5.66
mols O = 15.09/16 = 0.943
So the formula is C6.60H5.66O0.943; however, we know that the ratio should be small whole numbers; therefore, we convert these in the same ratio to make them small whole numbers. The easy way to do that is to divide the three numbers by the smallest of the three; i.e.,
C = 6.60/0.943 = 6.999 which rounds to 7.
H = 5.66/0.943 = 6.002 which rounds to 6.
O = 0.943/0.943 = 1
The empirical formula then is C7H6O