What is the empirical formula for a compound containing 26.57 g potassium, 35.36 g chromium, and 38.07 g oxygen?
Find the number of moles for each element by dividing the mass present with the relative mass of the atom.
Now divide each number of moles by the lowest one, in this case
Round to the nearest whole number
Note that NORMALLY you would NEVER be given the percentage oxygen. Why not? Because there are very few ways to measure the proportion of this gas. At a 1st year undergrad level this question would have proposed an oxide of chromium that contained
When we divide thru by the lowest number of moles (
But by definition, the empirical formula is the simplest WHOLE number ratio defining constituent atoms in a species, so we must double this provisional formula to give:
And this is a crystalline, orange powder, that is widely used in oxidations of organic materials....