Given a solution of ammonium chloride. What additional reagent or reagents are added to prepare a buffer from the ammonium chloride solution?
I know the answer is NaOH but I don't know why. Can someone explain this to me please?
Isn't ammonium chloride an acidic salt? It forms a weak acid in solution.
If I had NH4Cl, I would made a buffer by adding NH3. The NH4Cl/NH3 makes a GOOD buffer.
To prepare a buffer solution from an ammonium chloride solution, sodium hydroxide (NaOH) is added. The reason for adding NaOH is to create the conjugate base of the weak acid NH4+.
Ammonium chloride (NH4Cl) is a salt that dissociates into ammonium ions (NH4+) and chloride ions (Cl-) in solution. The ammonium ion acts as a weak acid that can donate a proton. When NaOH is added, it dissociates into sodium ions (Na+) and hydroxide ions (OH-) in solution.
The hydroxide ions from NaOH react with the ammonium ions (NH4+) to form water and the conjugate base of NH4+, which is ammonia (NH3). The balanced chemical equation for this reaction is:
NH4+ + OH- → NH3 + H2O
The formation of ammonia removes some of the ammonium ions from the solution, which helps to shift the equilibrium between the weak acid (NH4+) and its conjugate base (NH3) towards the base side. This shift in equilibrium results in the formation of a buffer solution.
In summary, by adding NaOH to an ammonium chloride solution, you are essentially creating a buffer by converting some of the ammonium ions into their conjugate base, ammonia. This buffer solution can then resist changes in pH when small amounts of acid or base are added.
To prepare a buffer solution from ammonium chloride (NH4Cl), one needs to add a suitable conjugate base. In this case, the appropriate conjugate base is sodium hydroxide (NaOH).
The reason NaOH is added is to provide hydroxide ions (OH-) that will react with the ammonium ions (NH4+) from the ammonium chloride solution. The reaction that takes place is as follows:
NH4+ + OH- → NH3 + H2O
The ammonium ions (NH4+) react with the hydroxide ions (OH-) to form ammonia (NH3) and water (H2O).
The ammonia produced in this reaction acts as the conjugate base for the buffer system. It can accept protons (H+) and then revert back to ammonium ions (NH4+). This will help resist changes in the pH of the solution when small amounts of acid or base are added.
Therefore, by adding NaOH to the ammonium chloride solution, it allows for the establishment of the NH3/NH4+ buffer system, providing a solution that can maintain a relatively constant pH when acid or base is added.
In summary, NaOH is added to the ammonium chloride solution to form ammonia (NH3), which acts as a conjugate base, establishing a buffer system that helps maintain the solution's pH.