# What is the [#OH^-#] in a solution of pH 3.00?

##### 1 Answer

#### Explanation:

For this answer, we use the formula:

We can write that like this:

Since pH=3 is given, we calculate pOH

Now the

We obtain:

For more information about pH, check here!

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**How is #pH+pOH =14# established? **

In water, the following (ionization) reaction occurs:

Therefore the equilibrium can be written like

Since water is the solvent here, we do not take the concentration of water into consideration (is very big). We obtain the following expression:

The

This means we can say:

To get from the

The same is true for the

Now if we take the Log from both sides of the

A mathematics rule tells us that multiplying inside the logarithm function is the same as adding these logarithms. Therefore we get

And now we can use the definitions of pOH and OH! We get:

with

Which is the same as