Video Transcript
In a chemical compound containing
carbon, oxygen, and hydrogen, there are equal numbers of carbon and hydrogen
atoms. However, the number of oxygen atoms
is twice the number of hydrogen atoms. What is the empirical formula of
the compound?
The empirical formula of a compound
tells us the simplest whole number ratio of atoms that are in the compound. Our compound contains carbon,
oxygen, and hydrogen. So, we need to figure out the ratio
of carbon to oxygen to hydrogen so we can determine the empirical formula of this
compound. We’re told that there are an equal
number of carbon and hydrogen atoms, which means that the ratio of carbon to
hydrogen in our compound is one to one. Then the problem says that the
number of oxygen atoms is twice the number of hydrogen atoms. In other words, the ratio of oxygen
to hydrogen in the compound is two to one.
If we put both of these pieces of
information together, that means that the ratio of carbon to oxygen to hydrogen
that’s in this compound is one to two to one. We can’t reduce this ratio any
further, which means that it’s already expressed in the simplest whole numbers. So, we can use this ratio to create
the empirical formula for the compound, CO2H. Because this formula just tells us
the ratio of carbon to oxygen to hydrogen in the compound, that doesn’t necessarily
mean that there’s one carbon atom, two oxygen atoms, and one hydrogen atom in the
compound.
The type of chemical formula that
does tell us that information is the molecular formula, which tells us the amount of
each type of atom in the compound, not just the simplest whole number ratio of
atoms. But we were just tasked with
finding the empirical formula of this compound, which is CO2H.
