acid to least acidic?

Question

Ch4, H2O, HF, NH3

list from most acidic to least acidic.
Please also help to explain why they are in that order, does it have anything to do with their hydrogen atoms?

Answer 1

Acidity is based on H+ ion concentration in a water solution. A molecule has to produce hydrogen ions when placed in water in order to be called an acid.

HF forms some H+ ions and is an acid
H2O forms some H+ ions in itself (its called autoionization) but the number is lwo (1 x 10^(-7))

CH4 doesn't form any H+ in water (its a covalent gas)

NH3 actually REMOVES H+ from water (when it forms NH4+) so it would have a lower H+ concentration than water and is a base.

Answer 2

Acidic levels are based on PH, meaning the inverse log of the Hydrogen Ion Concentration, Ammonia, NH3 is a base, H2O is water, that is a neutral, Hydrofluoric Acid, HF, is acidic and Methane, CH4 is not very reactive, so I would say the order would be from most acidic to least, HF, CH4, H2O, and NH3.