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# PH of 10^-9 M H2SO4 watch

1. Like the title says, how do you calculate the PH of 10^-9 M H2SO4??
The final answer is around 7, but I don't know how to get that answer.
2. (Original post by AntiClock)
Like the title says, how do you calculate the PH of 10^-9 M H2SO4??
The final answer is around 7, but I don't know how to get that answer.
Full dissociation so: pH = -log10 [H+]

So for every mol of H2SO4 you'll have twice the H+.
3. pH = -log10 [H+]

Assume it fully dissociates, so the [H+] is 2 x 10^-9. Plug that into the formula above!
4. (Original post by Revd. Mike)
pH = -log10 [H+]

Assume it fully dissociates, so the [H+] is 2 x 10^-9. Plug that into the formula above!
-log(2x10^-9)=8.6, but the answer say it's 7. So, I guess it's a mistake on the answer key then.

A more complex question if I may, what's the PH of:
1.0 liter of 0.1M glycine hydrochloride (pka are 2.3 and 9.7) to which as been added 100ml of 1M NaOH.
5. You need to take into account the H+ ions in water in this case (you're never going to have an acidic solution that has a pH > 7 !).

Kw = [OH-][H+] = 10-14 so [H+] = 10-7 (from the water) + 2 x 10-9
6. H2SO4 definitely has a ph lower than 7.

The name sulphuric acid kind of gives that away, you'd think.
7. (Original post by EierVonSatan)
You need to take into account the H+ ions in water in this case (you're never going to have an acidic solution that has a pH > 7 !).

Kw = [OH-][H+] = 10-14 so [H+] = 10-7 (from the water) + 2 x 10-9
(Original post by ste_mc_efc)
H2SO4 definitely has a ph lower than 7.

The name sulphuric acid kind of gives that away, you'd think.

1.0 liter of 0.1M glycine hydrochloride (pka are 2.3 and 9.7) to which as been added 100ml of 1M NaOH.

I hate these stupid PH questions in biochem
8. Work out how many moles of glycine, HCl and NaOH you have to start with then work out how much of each you'll have once they're added. Go from there

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Updated: February 10, 2010
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