Question

Write a reaction showing how NaHCO3 and Na2CO3 buffer would neutralize added NaOH

Answer 1

A buffer of NaHCO3 and Na2CO3 is made by mixing the two components in an aqueous solution. The mixture of these two components would result in a buffer of a weak acid and its conjugate base. A weak acid like NaHCO3 sparsely dissociated in aqueous solution, and its conjugate base sodium carbonate rarely takes up a proton from the solution.

But in the presence of added acid or base, its buffer activity starts working. If a strong base like NaOH is added to the buffer, the weak acid will dissociate and the H⁺ ions released will convert the base in water and conjugate acid.

NaHCO3 + OH^- = NaCO3^- + H2O

NaCO3^- + Na⁺ = Na2CO3

Since the added hydroxide ions are consumed by the protons dissociated from the weak acid, the pH of the solution barely changes and thus the solution acts as a buffer. The added NaOH will dissociate into sodium and hydroxide ions. Na ions form Na2CO3 with the conjugate bas eof the acid NaHCO3 and hydroxide gets converted into water.