At the beginning, i calculated [OH-] and [H+].
First acid...
pH= 0,22
[H+] =0,603 mol/l
Next base;
pH=13,3
[OH-] = 0,2 mol /l
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For example we have 1l base and 1l acid. Our solution is 2 l. How many H+ is there? 0,6 - 0,2= 0,4 /2
So, pH= 0,7??
I'm not sure.