adjust the pH of a solution

[lightyear]

How to adjust the pH of cholindihydrogen phosphate solution with phosphoric acid to 4.0, 4.5, 5.0, and 5.5?

 

cholindihydrogenphosphate is a type of ionic liquid with the following formula:

[ce] HO(CH2)2N(CH3)3^+ [/ce] [ce] H2PO4^- [/ce]

Can I calculate it using the Henderson-Hasselbalch equation?

Edited December 14, 2008 by lightyear

[hermanntrude]

you're gonna need some pKa data, i suspect

[John Cuthber]

You are going to need pKa data measured in that ionic liquid too.

Good luck finding any.

[hermanntrude]

You are going to need pKa data measured in that ionic liquid too.

Good luck finding any.

 

nah it's a solution of the ionic liquid. I think that as long as it's fairly dilute we should be OK to only consider the pKa in water

[John Cuthber]

Rereading the question I see that no solvent is specified. Could be in horse urine for all we know.

If it is a dilute solution in water then you can assume that the quaternium salt is a strong base then you only need to know the acidity constants for the phosphoric acid/ phosphate system

[hermanntrude]

I think it's safe to assume this question was asked by a biologist. Only a biologist would leave so many vital parts of the question out.

[lightyear]

there is no pKa data of the ionic liquid i mentioned before.

80 g/L solution of this ionic liquid in water has the pH of 5.0.

molar mass 201.16 g/mol

can I calculate the acid volume needed? Is titration the only solution?