A 17.59 g sample of a compound contains 5.61 g potassium (K), 5.09 g chlorine (Cl), and oxygen (O). Calculate the empirical formula.

Question

chemistry

Answer 1

1. Find the weight of Oxygen

Use the total weight and determine the amount of oxygen in the sample. 

 

(17.59-5.61-5.09=?)

 

 

2. Determining the Empirical Formula
Start with the number of grams of each element.
Convert the mass of each element to moles using the molar mass from the periodic table.
Divide each mole value by the smallest number of moles calculated.
Round to the nearest whole number.

 

This is the mole ratio of the elements and is represented by subscripts in the empirical formula.

If the number is too far to round (x.1 ~ x.9), then multiply each solution by the same factor to get the lowest whole number multiple.
(e.g. If one solution is 1.5, then multiply each solution in the problem by 2 to get 3. )
(e.g. If one solution is 1.25, then multiply each solution in the problem by 4 to get 5.)