I think that titrating NH3 with HCl solution has a neutral equivalence point where the pH = 7.0. Is this right?
No, the equivalence point will be on the acid side of 7.0. Let me show you a very good way to know, it works every time, but it isn't very well accepted.
The REAL way is to know what are Bronsted-Lowry acids/bases.
The reaction is NH3(aq) + HCl(aq) ==> NH4Cl(aq) so the pH at the equivalence point is determined by the pH of the salt, NH4Cl.
So the REAL way is to know that NH4^+ is a stronger acid than H2O and the hydrolysis reaction is
NH4^+ + H2O ==> H3O^+ + NH3
and you can go through the acid/conjugate base thing. The H3O^+ tells you it is acidic.
Here is the way I know.
NH4Cl + HOH ==> NH4OH + HCl
NH4OH is a weak base (it has Kb = that of NH3). HCl is a strong acid. We know that. So the strong acid wins out over a weak base and the salt will be acidic.
Another example. sodium acetate
CH3COONa + HOH ==> CH3OOH + NaOH
Acetic acid, CH3COOH, is a weak acid. NaOH is a strong base so the salt will be basic (and it is when acetic acid is titrated with NaOH).
No, your statement is not correct. Titrating NH3 with HCl solution will not have a neutral equivalence point at pH 7.0. The reaction between NH3 and HCl is an acid-base reaction, with HCl being a strong acid and NH3 being a weak base.
When NH3 reacts with HCl, it forms NH4+ (ammonium ion) and Cl- (chloride ion). In the beginning, before any reaction has occurred, the NH3 solution will be basic with a pH greater than 7.
As HCl is slowly added, it reacts with the NH3 to form NH4+ ions, which decreases the hydroxide ion concentration and increases the acidity of the solution. The pH will gradually decrease as more HCl is added.
At the equivalence point, all the NH3 has been consumed and the solution will contain only NH4+ ions. However, at this point, the solution will still be acidic due to the presence of excess HCl. The pH will be much less than 7.
Therefore, in the titration of NH3 with HCl, the equivalence point will be acidic and the pH will be less than 7.
To determine whether the titration of NH3 (ammonia) with HCl (hydrochloric acid) has a neutral equivalence point at pH 7.0, we need to consider the chemical reaction involved and the properties of the substances.
Ammonia reacts with hydrochloric acid according to the following balanced equation:
NH3 + HCl → NH4Cl
In this reaction, ammonia (NH3) acts as a base and hydrochloric acid (HCl) acts as an acid. The reaction produces ammonium chloride (NH4Cl).
Ammonia is a weak base, which means that it partially dissociates in water. When ammonia reacts with water, it forms hydroxide ions (OH-) and ammonium ions (NH4+). The hydroxide ions increase the pH of the solution, making it more basic.
Hydrochloric acid, on the other hand, is a strong acid that ionizes completely in water to yield hydrogen ions (H+). The hydrogen ions decrease the pH of the solution, making it more acidic.
During the titration, as hydrochloric acid is added to the ammonia solution, the hydroxide ions from ammonia react with the hydrogen ions from hydrochloric acid to form water. This neutralizes the pH and brings it closer to 7.0.
Therefore, it is expected that the pH at the equivalence point of the titration of NH3 with HCl will be close to 7.0, but it might not be exactly 7.0. The actual pH value will depend on the concentrations of the starting solutions and the amounts of reactants.
To know the exact pH at the equivalence point, it is necessary to perform the titration experimentally and measure the pH using a pH meter or indicator.