Why is a solution of KNO3 neutral and not acidic?
K^+ doesn't hydrolyze (H2O has a stronger attraction for the OH- than K^+) and NO3^- doesn't hydrolyze (H2O is a stronger base than NO3^- meaning that H2O will not donate a proton to NO3^-).
Looking at it another way, suppose it did, what would we get?
KNO3 + HOH ==> KOH + HNO3.
BUT KOH is a strong base and HNO3 is a strong acid and there is no driving force for the reaction to occur. Remember, three reasons for a reaction to go to completion:
1. gas is formed (neither is a gas).
2. ppt is formed (neither is a ppt).
3. slightly ionized substance is formed (neither is a weak electrolyte).
So, no reaction when KNO3 is placed in water, except for the crystal structure breaking and forming K^+(aq) and NO3^-(aq).
A solution of KNO3 (potassium nitrate) is neutral because neither the K+ ion nor the NO3- ion hydrolyzes significantly in water.
When a substance hydrolyzes, it reacts with water molecules and forms new species. If the K+ ion were to hydrolyze, it would react with water, but water has a stronger attraction for the OH- ion than for the K+ ion. Therefore, water will not donate a proton to the K+ ion, and no reaction occurs.
Similarly, if the NO3- ion were to hydrolyze, water would act as a stronger base than the NO3- ion. This means that water will not accept a proton from the NO3- ion, and no reaction occurs.
If we assume for a moment that hydrolysis does occur, and the reaction would be KNO3 + H2O ā KOH + HNO3. However, KOH is a strong base and HNO3 is a strong acid. Since no driving force exists for this reaction to occur, it will not proceed to completion.
In summary, when KNO3 is placed in water, the crystal structure breaks down, and K+ and NO3- ions are formed in the solution. These ions do not undergo significant hydrolysis, and therefore, the resulting solution is neutral.