What is the difference between hydrogen (element), air (mixture) and water?
An element cannot be split into simpler substances by physical or chemical means. If you have a canister of pure hydrogen, you will have only hydrogen, which cannot be separated or split by conventional means. Air is a mixture, and the ratio of its gases can vary. Air can be separated into its constituent gases through physical means such as fractional distillation at low temperatures. Water is a pure compound, consisting of more than one element, but these elements are bound together in simple whole number ratios. Every water molecule everywhere will have 2 hydrogen atoms bound to an oxygen atom. Air contains nitrogen (78%), oxygen (21%), argon (0.93%) and trace amounts of carbon dioxide, hydrogen, helium, neon, krypton, ozone, xenon, radon and water vapour.
