Give a reason for each of the following :
The number of hydrogen ions in an aqueous solution of acetic acid increase considerably with dilution while this is not the case with an aqueous solution of hydrogen chloride.
Give a reason for each of the following :
A mixture of NH4Cl and NH4OH is used to precipitate the metallic hydroxides of group III.
Arrange the following in increasing order of acidity and explain your order:
Phenol, Methanol, Water.
The correct increasing order of acidity is Methanol <Water <Phenol.
Proton donors are acids. In methanol (CH3OH), methyl is electron donor group and it increases the electron density between O—H bond. As a result, the formation of H+ becomes difficult and therefore methanol is least acidic among methanol, water and phenol. In the case of phenol, benzene ring withdraws electrons towards itself and therefore decreases electron density between O—H bond. The removal of H+ becomes very easy, therefore phenols are most acidic among methanol, water and phenol. Water has neither electron density increasing nor electron density decreasing the effect.