# What is the #pH# of a solution whose concentration is #0.450*mol*L^-1# in ammonia; #K_b=1.80xx10^-5#?

##### 1 Answer

#### Explanation:

We interrogate the equilibrium:

We set up the equilibrium in the usual way:

And we call the concentration of ammonia that hydrolyzes

And thus:

If, we assume that

Clearly I am making a meal of the successive approximations, but I think you can get the gist of the operation. Approximate, then substitute, then resubstitute, till you reach a consistent answer. Alternatively, you could have used the quadratic equation, but here there are more terms to include, and more mistakes (potentially) to make.

And thus at equilibrium,

And, since in aqueous solution,

If I were you, I would apply this general method to other