A buffer system is created by neutralizing the supernatant solution containing Pb^2+, Fe^3+, Al^3+, Ca^2+, Cu^2+, and K^+ ions with 6M NH3 solution and then adding an equal volume of 6M NH3 solution. Explain what forms of 6M NH3 were present in the final solution, their concentrations, and how they could function as a buffer. Please help. I do not understand this questional at all.

I don't understand it either. You appear to have typed part of a line twice. If that extra 6M NH3 (equal volume added) is part of the question, the solution forms Pb(OH)4^2- from Pb(OH)2, Cu(OH)4^2- (from Cu(OH)2), and those could act as buffers.

To understand this question, let's break it down step by step.

Step 1: Neutralizing the supernatant solution
The initial supernatant solution contains various ions, including Pb^2+, Fe^3+, Al^3+, Ca^2+, Cu^2+, and K^+. Neutralizing this solution means adding a substance that can react with these ions and bring their overall charge closer to neutral. In this case, 6M NH3 (ammonia) solution is used.

Step 2: Adding an equal volume of 6M NH3 solution
After neutralization, an equal volume of 6M NH3 solution is added to the supernatant solution. This means that the concentration of NH3 in the final solution will be 6M as well.

So, in the final solution, there are two forms of 6M NH3 present:
1. NH3 molecules (ammonia)
2. NH4+ ions (ammonium)

Now, let's address how these forms of NH3 could function as a buffer.

A buffer is a solution that resists changes in pH when an acid or base is added to it. Buffers typically consist of a weak acid and its conjugate base, or a weak base and its conjugate acid.

In this case, the NH3 molecule is a weak base and can accept a proton (H+) to form the NH4+ ion, which is its conjugate acid. This equilibrium reaction is represented as follows:
NH3 + H+ ⇋ NH4+
The NH3 molecule acts as the base, and NH4+ acts as the conjugate acid.

When an acid is added to the buffer solution, it will react with NH4+ by donating H+ ions, shifting the equilibrium to the left, and preventing a large change in pH. Similarly, when a base is added, it will react with NH3 by accepting H+ ions, shifting the equilibrium to the right, and helping maintain the pH.

In this case, the 6M NH3 solution, which includes both the base (NH3) and its conjugate acid (NH4+), can act as a buffer to resist changes in pH when small amounts of acid or base are added to it.

To summarize, the final solution contains NH3 molecules and NH4+ ions, both with a concentration of 6M, and these forms can function as a buffer by maintaining the pH of the solution even when small amounts of acid or base are added.