Chemical Forums

Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: jeffmoonchop on May 17, 2019, 05:31:50 PM

Title: Effect of salt on pH
Post by: jeffmoonchop on May 17, 2019, 05:31:50 PM
Hi, I have buffered solution at pH 6.6 and I want to adjust the pH to above 7. Im using 20mM Tris 1M NaCl pH 8 to do so but when I try to adjust, the pH actually goes down. Is there an effect that salt has on the pH?

I'm guessing that the actual pH is above 7 but that the salt is interfering with the pH meter. How can I tell what the actual pH is when the salt is interfering?

I need salt in it for another application but I suppose I could reduce the salt concentration. I could titrate with lower salt to quantify the effect of salt on the actual pH.

So if I adjust with 20mM Tris pH 8 with no salt in it and the pH is 7.5, can I assume that if I do the same with salt present that the pH is 7.5, even if the meter reads 6.4?