Ibuprofen, the active ingredient in Advil, is made up of carbon, hydrogen and oxygen atoms. When a sample of ibuprofen, weighing 5.000 g, burns in oxygen, 13.86 g of CO2 and 3.926 g of H2O are obtained. What is the simplest formula of ibuprofen?

The empirical formula for the given compound is

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of

Mass of

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 13.86 g of carbon dioxide, of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 3.926 g of water, of hydrogen will be contained.

Mass of oxygen in the compound = (5.00) - (3.78 + 0.436) = 0.784 g

To formulate the empirical formula, we need to follow some steps:

Moles of Carbon =

Moles of Hydrogen =

Moles of Oxygen =

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.049 moles.

For Carbon =

For Hydrogen =

For Oxygen =

The ratio of C : H : O = 6 : 9 : 1

Hence, the empirical formula for the given compound is