Question

How does this process of standardization of NaOH works and why is KHP used (what does "KHP" stand for and what does the molecule look like?). Why was it necessary to standardize NaOH?

Also, we used Phenolphthalein as an indicator. Find out what it looks like [show in the structure(s)] and what is the acid/base mechanism that leads to the pink color you observed.

Answer 1

Phenolphthalein is basically an indicator used for the detection of a end point or we can say for the completion of rxn from our naked eye .

The structure of phenolphthalein is :

As according to the above structure we can say phenolphthalein is having two H+ions i.e two replaceable H+ions.....

Before writing a chemical equation a most important thing about this reaction is :

a) phenolphthalein is a weak acid ,so in a chemical reaction it will be in equilibrium with its ionic form

​so in this chemical equation ,equilibrium will shift towards ionic I.e deprotonated form (phenolate ion form )...... B) Now the most important thing why phenolphthalein gives color ,it will be clear according to the next image

And now the equation of phenolphthalein in basic medium is:

And the last image will give you the complete information about reactions of phenolphthalein in different mediums.