Question

A 18.21 g sample of a compound contains 5.81 g potassium (k), 5.27 g chlorine (cl), and oxygen (o). calculate the empirical formula.

Answer 1

To determine the empirical formula of the compound given, we need to determine the ratio of the elements present in the compound. To do that we use the given amount of sample of the compound and the masses of each of the element included. Then, we calculate for the number of moles of each element. We do as follows:
mass moles
Potassium 5.81 0.1486
Chlorine 5.27 0.1487
Oxygen 18.21 - 5.81 - 5.27 = 7.13 0.4456

Dividing the number of moles of each element with the smallest value of number of moles, we will have the ratio of the elements:

K = 1 Cl = 1 O = 3

Therefore, the empirical formula would be KClO3.