Determine the formula of a substance in which the mass fraction of carbon is 27.27%, and oxygen is 72.72%

Let’s find the mass of oxygen in the substance:

100 g of substance – 100%,

x oxygen – 72.72%,

x = (100g x 72.72%): 100%

x = 72.72 g.

We find the mass of carbon in the substance.

100 g – 100%,

x – 27.27%.

x = (27.27% x 100g): 100% = 27.27g.

Let’s find in what proportions carbon and oxygen are in the substance. To do this, divide the mass of an element by its atomic mass.

C: O = (27.27: 12): (72.72: 16) = 2.27: 4.54 = 1: 2.

We get that carbon and oxygen are in the ratio 1: 2. The formula is СО2.