# Hydrogen ions and ph relationship to pka

### How to Determine pH From pKa | Sciencing

A pKa of 2 for substance “X” means that at a pH of 2, free Hydrogen ions are available in a solution, and pH and pKa are related by the following equation. This equation is often used to determine the proportion of conjugate base [A H. pH and. ] log[ a a. K. pK −= While the definition of pKa is given above, the functional proportion of the fluoride ion to the hydrofluoric acid would be This equation is: pH = pKa + log[A-]/[AH], where [AH] is the of hydrogen," and it's a measure of the concentration of hydrogen ions in an.

## 1.17 pka and pH

So I'm actually going to get rid of the log by raising both sides to the 10th power. So what does this tell us? It may not look like it tells us a whole lot more, but actually, it tells us a lot.

It tells us about the relative relationship and size between A minus and HA concentration. So if we look at this, we can derive a couple relationships. So let's go ahead and look at all the possible scenarios for these three things.

So anything to the zeroth power is equal to one. Which tells us that this ratio is equal to one. And if A minus concentration over HA concentration is equal to one, that means that they have the same concentration.

I forgot a minus sign there. This is a really helpful thing to remember. And this comes up a lot not just when you're talking about buffers by themselves, but also when you're doing titrations.

pH, pOH, H3O+, OH-, Kw, Ka, Kb, pKa, and pKb Basic Calculations -Acids and Bases Chemistry Problems

And the point in your titration where the HA is equal to A minus is called the half-equivalence point. And if you haven't learnt about buffers, that's okay. Oh, sorry, if you haven't learn about titrations yet, that's fully fine.

Just ignore what I just said laughsbut if you have, the moral is just that, this is a really, really important relationship that is really helpful to remember. And I said really a lot there.