# Determining the pH of an organic solvent

Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $$\mathrm{p}K_\mathrm{a}$$ of those groups. However,

• How would you determine or calculate the $$\mathrm{pH}$$ of an organic solvent?

An alternative way of asking this question is how would one calculate the concentration of hydronium ions or free protons in a nonaqueous solution.

• I think a good first step to answering this question would be to identify exactly what ion is formed by the addition of protons to chloroform. Hydromium ions can't exist without water (is the system open to atmospheric water vapor?). Maybe one or more of the Cl atoms on the solvent gets protonated. – Pat Apr 27 '12 at 14:08
• No. I'm suggesting that you measure its electrophoretic mobility, $\mu_{ion}= \frac{q}{f}$. Once you know the friction coefficient, $f$, then you can determine its charge, $q$. – Chris May 10 '12 at 1:20