What is the pH of a 0.0050 M solution of sodium fluoride?

Question

I got 7.58 for pH.

Is it correct? but I try to plug in my quadratic formula, I don't get the pH 7.58.

I'm really confuse.

Please help.

Answer 1

I can't check your answer because you don't give the Ka value you used for HF. Books differ with tables for Ka and Kb. I obtained 7.42 for pH If you will post your work I will check it.

Answer 2

oh Ka is 3.5x10^-4. Sorry about that

Answer 3

@Dr.Bob222 I was answer that answer before but it was wrong

Answer 4

I don't understand your last post. Using 3.5E-4 for Ka, that 7.58 you calculated is correct. I calculated it with and without the quadratic formula and got the same answer.