I'm trying to determine the (theoretical) end-point for a titration of paracetamol with KOH. So I need to work out the volume of 0.1M KOH required to neutralise 125mg of paracetamol.

 

Information about the practical this is based on:

This 125mg of paracetamol tablet is crushed and dissolved in 100cm3, then 25cm³ of this solution is pipetted into a beaker. Titrate this with 0.1M KOH and find the end point.

 

 

I have a method of doing this but I'm not sure it's correct:

 

0.125g/ 151.09gmol^-1 = 8.27*10^-4 mol paracetamol in 100cm³ solution.

 

8.27*10^-4 mol/ 4 = 2.07*10^-4 mol paracetamol in 25cm³ solution (the 25cm³ pipetted into a beaker).

 

 

We are told that the conc. of KOH is 0.1M.

 

With the information available here I said:

 

0.1M/1000*(x) = 2.07*10^-4 mol

 

I rearranged the above to find 'x', which is the volume of solution required to make the same amount of moles that there are of paracetamol, hence enough to neutralise it:

 

(1000*(2.07*10^-4))/0.1 = x = 2.7cm³ of KOH required.

 

 

 

Is this remotely correct? If not can someone help me out?

 

Thanks in advance.

Edited February 16, 201312 yr by Iota

I didn't check your math, but the way you've done it looks fine to me.

I've double checked the maths then checked it again, should be all right! Thanks.

Just went over this problem, and yes everything seems to be correct.