# How do I find #pH# and #pOH# for solutions of aqueous hydrogen fluoride or sodium fluoride?

##### 1 Answer

You have the measurements, but you must use the definitions of

#### Explanation:

Water dissociates according to the following equilibrium:

Now it is well known that for a given temperature, the extent of this autoprotolysis reaction is a constant:

And we can simplify this to

By careful measurement we know that

Now this is a mathematical expression, which we are free to manipulate, provided that we do it to BOTH sides of the equation. Now we can take

But by definition

And also by definition

So we get our defining relationship:

So get an electronic calculator, and have a go at your table. You will need