Is this a correct example of when CO2 interferes with acid base titration? If not, what is?
CO2 + H2O → H2CO3
1 answer
Yes it is; however, only in cases where CO2 is generated in the titration; e.g. when carbonates (Na2CO3, CaCO3, etc) are being titrated with an acid such as HCl or H2SO4. Typically this is handled, when titrating to a methyl red end point, is to add acid until the methyl red changes to the acid color, then heat the solution to drive the CO2 out of solution which raises the pH back above the end point, then titrate slowly to the end point. You get a sharp color change here since the weak acid is no longer present in large quantities.