I am a bit confused on buffers: If I have a solution with a weak acid (say $\ce{NH4}$) and its conjugate weak base ($\ce{NH3}$), I have a buffer solution (in $\ce{H2O}$).
$$\ce{NH4 <--> NH3 + H+}$$
But now If I add a strong base to my solution ($\ce{OH-}$ for example) I get that my pH will go up but I don't understand the dynamics of it.
- Will my added $\ce{OH-}$ react with the weak acid $\ce{NH4}$ (more $\ce{NH3}$ produced)?
$$\ce{NH4+OH -> NH3 + H2O}$$
- OR will my added $\ce{OH-}$ react with the $\ce{H+}$ produced by my weak acid (Less $\ce{H+}$ produced)?
$$\ce{NH3 + H+ (products of $\ce{NH4}$) + OH- -> NH3 + H2O}$$
I understand that both cases up end up with the pH going up but but I want to be sure to understand with what exactly my $\ce{OH-}$ molecule reacts once added to my solution.
Is it the $\mathrm{1^{st}}$ reaction which means more $\ce{NH3}$ produced?
Or is it the $\mathrm{2^{nd}}$ reaction which means less $\ce{H+}$ produced?