Ethanol Chemical Formula

The chemical formula of ethanol is C2H5OH. It can also be written as CH3-CH2-OH. It is a straight chain alcohol. It is a carbon of a methyl group (CH3-) attached to the carbon of methylene group (-CH2-), which if further attached to the oxygen of a hydroxyl group (-OH). EtOH is used as an abbreviation for ethanol where the ethyl group (C2H5) is substituted by Et.

The structural formula of ethanol is CH3CH2OH. The molecular formula of ethanol is C2H6O. And the chemical formula of ethanol is C2H5OH. The chemical formula can be used to interpret mole ratios and mole fractions. The ratio of hydrogen to carbon is essential if a comparison between the fuels has to be made. The hydrogen to carbon ration of ethanol is 6:2 that is 3.0. Mole fractions can also be calculated. Mole fraction is of an element is the number of atoms of the element divided by the total number of atoms in the formula unit. In case of ethanol, the formula unit contains nine atoms. We find the mole fraction of carbon and ethanol. Ethanol has two atoms of carbon. Thus, the mole fraction of carbon in the ethanol compound is 2 divided by 9 which equals to 0.22. Further the mole percentage can be calculated by dividing 2 by 9 and then multiplying by 100. It is 22 per cent. This means that 22 per cent of the atoms in ethanol are carbon. Similarly in case of hydrogen, the mole fraction is 6 divided by 9 which equals to 0.67 and the mole percentage is 67 per cent. For oxygen, the mole fraction is 1 divided by 9 which equals to 0.11 and the mole percentage is 11 per cent. The chemical formula of ethanol can also be interpreted in terms of masses of the elements of the compound.

We can find the masses of carbon, hydrogen and oxygen in one mole of ethanol by using the atomic weights or molar masses of these three elements, carbon hydrogen and oxygen. In case of carbon, its mass is (2 mol) (12.0 g mol–1) which equals to 24 g. In case of hydrogen, its mass is (6 mol) (1.01 g mol–1) which equals to 6 g.

Finally, in case of oxygen its mass is (1 mol) (16.0 g mol–1) which equals to 16 g. Thus, one mole of ethanol has 24 g of carbon, 6 g of hydrogen and 16 g of oxygen. The mass fraction of the compound can also be determined with the chemical formula. The mass fraction of an element in the compound is the ratio of the mass of that element to the mass of the whole formula unit. The total molar mass of ethanol is (24 g of carbon + 6 g of hydrogen + 16 g) mol–1 of oxygen. This equals to 46 g mol–1. In case of the mass fraction of oxygen, it is 16 g divided by 46 g which equals to 0.35 g. In case of the mass fraction of hydrogen, it is 6 g divided by 46 g which equals to 0.13 g. In case of the mass fraction of carbon, it is 24 divided by 46 which equals to 0.52 g. We can convert the mass fraction into the mass percentage. For oxygen, the mass percentage is 0.35 multiplied by 100 which equals to 35 per cent. Similarly the mass percentage of hydrogen is 13 per cent and the mass percentage of carbon it is 52 per cent.