Why the distilled water used in PH experiment had to be boiled before use?

Question

Hit: A gas could be dissolved in the water that might affect its pH.

Answer 1

Any carbon dioxide (CO2) dissolved in the water would form a buffer system: CO2 + H2O --> H2CO3 = HCO3- + H+

This would interfere with the accurate pH measurement of solutions prepared IN this water because of the presence of the buffer system, which could compete with other systems.

Answer 2

Probably to drive out any dissolved carbon dioxide that might be present (would affect sensitive pH work).

Answer 3

To expel CO2 from distilled water, D.W. has to boil for more than 15 minutes.After boiling it has to be cooled in soda lime tube.