A compound contains 40% calcium, 12% carbon, and 48% oxygen by mass. What is the empirical formula of this compound?
Although you have not been provided with direct masses, you can use the percentage composition values in place of masses.
First, calculate the number of moles of each element:
Your next step would be to divide by the smallest value, but since this is
This is the formula for the ionic compound calcium carbonate, confirming that our result is indeed in the magnitude of a plausible answer. In fact, given the fact that calcium carbonate is ionic, it is also true that this empirical formula equates to the unit formula of the compound.