The gaseous mole fraction of ammonia is given by the ratio of the amount of ammonia to the total amount of gas present. At room temperature, water is a liquid. Since each substance is present in only one state, it can be assumed that the water occupies no volume and exerts no pressure as water vapor. The mole fraction of is therefore
(10) What is the partial pressure of ?
The partial pressure of ammonia is given by the product of the mole fraction and the total pressure: