04-11-2018, 11:38 AM

I got this problem wrong on my computer homework and I can't figure out why.

The problem states that we have a 0.25M HF and 0.10M NaF solution. We are given the Ka of HF = 6.8e-4 Our goal is to find the pH.

I started out by creating an ICE table for the reaction HF ::equil:: H+ + F-.

After filling out the ICE table I got the equation

Ka=6.8e-4 = ((0.10+x)x)/(0.25-x)

Solving for x I got 1.7e-3, which I used as the [H+] to get a pH of ~2.7.

I can't figure out where exactly I went wrong. Can anyone point out my mistake?

Thanks

The problem states that we have a 0.25M HF and 0.10M NaF solution. We are given the Ka of HF = 6.8e-4 Our goal is to find the pH.

I started out by creating an ICE table for the reaction HF ::equil:: H+ + F-.

After filling out the ICE table I got the equation

Ka=6.8e-4 = ((0.10+x)x)/(0.25-x)

Solving for x I got 1.7e-3, which I used as the [H+] to get a pH of ~2.7.

I can't figure out where exactly I went wrong. Can anyone point out my mistake?

Thanks