air is mixture while water is compound.how law of constant composition helps in explaining this fact?
Law of constant composition states that all samples of a given chemical compound have the same elemental composition by mass. Pure water (without any salts dissolved in it) is a compound with an exact composition (H2O), and air is mixture of different gases. All water samples have exactly the same composition. In the case of air, all samples will have significant differences in composition. For example in the city percentage of CO2 in the air is greater than in rural territory. Furthermore, the percentage of O2 is lower high up in the mountains as compared with it at the sea level. This is proof that air is a mixture with a variable composition.