That means we could use the lock formula to find the concentration of this guy. Now, after we find the concentration of this guy, the concentration of this guy is the same thing. That's because 1 mol and 1 mol, our ratio of this guy to this guy is one to one. So that means whatever the amount and molar of this guy is, this guy is the same. So let's find the concentration of hydronium. So, PH equals 3.5
to my given information is equal to negative log of the concentration of hydrogen.