Some students have said that a buffer is like a proton (H ) sponge. Evaluate this statement and explain both how a buffer is like a sponge and how it is not like a sponge. For your explanation, include chemical equations, data, and create and explain molecular-level drawings. (Question is taken from Orgill and Sutherland, 2008.) (Saloni)

i)  Buffer absorbs  H^+ and OH^- ions preventing large changes in pH when small amounts of acid or base is added but when large amounts of acid or base is added there will be a change in pH

ii) absorption of liquid is related to a chemical reaction for a buffer system but it is not related a chemical reaction for a proton( H ) sponge.

Explanation:

i) Buffer like a proton ( H ) sponge

Buffer absorbs  H^+ and OH^- ions preventing large changes in pH when small amounts of acid or base is added but when large amounts of acid or base is added there will be a change in pH

The pH of a Buffer follows the Henderson-Hasselbach model

pH = pKa + Log ([A-]/[HA])

when base is added

HA + OH^-   > A- + H2O

when acid is added

A^- + H^+   > HA

ii) Buffer not like a proton ( H ) sponge

absorption of liquid is related to a chemical reaction for a buffer system but it is not related a chemical reaction for a proton( H ) sponge.

6.4 cm (max) - 25 cm (min)