Under Dalton's law, we can use the mole fraction of a gas to find the partial pressure of that gas. Here we're going to say dolphins loss says that the partial pressure of a gas 1 equals the mole fraction of that gas one times the total pressure.
So if you don't quite remember how to calculate mole fraction, I suggest you go back and take a look at my topic videos on mole fractions before proceeding further under Dalton's law.
P 1 = X 1 × P total
