Question

How does dissolved CO2 in distilled water affect the accuracy of the determination of a NaOH solution's concentration? How is the term acid anhydride applied here?

I know you had answered this already, but what if KHP is used to titrate the NaOH. In this experiment KHP was used to standardize NaOH.

Answer 1

I tried to find the response I made to your earlier question but I can't find it. At any rate, it doesn't matter what is used to standardize the NaOH. What is important is how many of the H atoms of the H2CO3 formed you titrate. That depends upon what kind of indicator you use. With methyl red indicator both of the H atoms are titrated so there is no error. With phenolphthalein indicator (which is used for KHP vs NaOH) only one H of H2CO3 is titrated and there US an error. The molarity of NaOH will be too high (meaning that the concn NaOH actually is lower than you have calculated.) By the way, this has a name; it is called "carbonate error".