Strong base added changes pH?

can someone please help me with this and explain it to me? i'm not just asking for an answer; i'd like to actually know how to do this. thank you so much and the first correct answer will get a best answer!



a buffer is composed of NH3 and NH4Cl. how would this buffer solution control the pH of a solution when a small amount of a strong base is added?



1. the OH- reacts with the Cl-

2. the OH- reacts with the H2O

3. the OH- reacts with the NH4+

4. the OH- reacts with the NH3Strong base added changes pH?
The strong base OH- is going to react with the weak acid to form water and the conjugate base of the weak acid. So, OH- reacts with NH4+ to form water and NH3.



3 is the bet answer.Strong base added changes pH?
3. the OH- reacts with the NH4+



Because:



A buffer is either a weak acid or a weak base. ';Weak'; means not all of the compound forms ions. There is always a fixed ratio of ions to molecules. Ammonia reacts with water to form ammonium hydroxide, some of which forms ammonium ions and some of which stays as ammonium hydroxide molecules.



NH4OH %26lt;-%26gt; NH4(+) + OH(-)



A base is defined as a substance which forms hydroxyl ions in water. ';Strong'; bases exist almost entirely of ions. As more hydroxyl ions are added to the solution, it combines with the ammonium ions, forming ammonium hydroxide molecules. This effectively removes the base from solution and the pH will stay the same. This is how buffers work chemically.
A strong base needs to react with an acid. That acid may be either strong or weak.



1. The chloride ion is a neutral, spectator, ion when it comes to acid-base chemistry. There will be no significant interaction.



2. The water molecule can act as an acid, but the product of this reaction is just more OH-:



OH- + H2O = H2O + OH-



Skipping ahead



4. NH3 is a weak base. Bases react with acids, not other bases. There will be no significant interaction.



This leaves:



3. The NH4+ in NH4Cl is a weak acid, the conjugate acid of NH3. As long as the amount of added strong base is small the following reaction will proceed to completion with all of the OH- consumed:



NH4+ + OH- = NH3 + H2O



When the reaction is finished, there will still be unreacted NH4+ remaining along with additional NH3 produced. Thus, the system is only slightly perturbed. We start with a mixture of NH3 and NH4+, a weak base and it conjugate acid, and we end with a mixture of NH3 and NH4+. This is buffering.
3. NH4+ + OH- ===%26gt; NH3 + H2O



The pH goes up, but not by as much as it would if you added OH- to water.