[student78]

I have some praticals at school the other day to do with determening of the pKa values of methyl orange, phenolphthalein and aspirin. The teacher tried to explain the following question to use, but his answer made no sense to me. In the end he wasnt sure what the answer was.

Question: What would be a good indicator (methyl orange or phenolphthalein) to use for a titration of aspirin with 0.1M NaOH solution?

Any help would be greatly appreciated

Many thanks

[Borek]

What will be endpoint pH for aspirin titration?

[student78]

It was between 10 and 11.5 for me.
I think its 11.11

[Borek]

Which indicator changes color closee to this pH?

[student78]

For phenolphthalein its 10.06 and for methyl orange its 8.60.

[Borek]

Select the one that is closer to the endpoint and you are ready.

[student78]

Is there some sort of full explanation which i can use?

many thnks