Question

We developed a buffer solution from sodium hydroxide and acetic acid. Then we added HCl and NaOH to the buffer.  Write the chemical equations for the neutralizationformation of the buffer as well as reactions that occurred when HCL and NaOH were added to the buffer solution. Please write them thoroughly so that I can see step by step how each reaction occured and developed. Please type these equations. No handwritten work please and thank you.

Answer 1

Let us first look at the formation of the buffer system itself.

NaOH and acetic acid by itself does not form a buffer combination. The reaction of NaOH with

CH₃COOH helps set up the buffer. This is a neutralization reaction between a weak acid and a strong base to form salt and water.

Reaction involved:

CH₃COOH + NaOH   CH₃COO^-Na⁺ + H₂O

The actual buffer exists between CH₃COOH and its conjugate base CH₃COO^-.

Reaction when HCl is added to the buffer: the function of the buffer is to oppose any changes that we try to make to it.

If we add HCl, we are adding H⁺ ions to it which means it would try to reduce the concentration of H⁺ ions in solution. It can do this by :

CH₃COO^- + HCl CH₃COOH + Cl^-

Thus, adding HCl to the buffer would increase the concentration of CH₃COOH and decrease the concentration of CH₃COO^-.

Adding NaOH to the buffer: NaOH dissociates into Na⁺and OH^- ions in solution. If we increase the concentration of OH^- ions, the buffer would try to oppose the change.

It can do so by:

CH₃COOH + NaOH CH₃COO^- + Na⁺ + H₂O.

This means that adding NaOH to the buffer would increase the concentration of CH₃COO^- and decrease the concentration of CH₃COOH.