[prbablydougal]

I have been trying to calculate whether the pKa of methyl orange would change under different temperatures. I think i need to know whether the ionisation constant of methyl orange is positive or negative and what this value is, i can then see what effect changing the temperature would have. Is this correct??

My teacher gave me the equation:
 :delta:G = -RTxLn(Kp)

However dose this equation not apply to pressure??? is there a similar one for Ka?

thank you,