So Ka is equal to the concentration of this guy times the concentration of this guy divided by the concentration of this guy. So, 3.16
times ten to the negative four times 3.16 times ten to negative four divided by 0.2968 gives me 3.36
times ten to negative six. So that's our Ka. But we're not done because we want to find the PKA. So I simply use the log formula. So, PKA gives us negative log of this guy produces 5.47.