Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: SamstaUK on July 24, 2009, 10:49:04 PM

Title: Calculating pH
Post by: SamstaUK on July 24, 2009, 10:49:04 PM

Maybe this is too advanced for High School chemistry, but I'm curious.. How do you calculate the pH of a solution?

I saw the formula -log[H+]

What is H+?

Could someone show me a couple of examples, first with HCl, then with H2SO4?

What about H2O?

Title: Re: Calculating pH
Post by: Astrokel on July 24, 2009, 11:15:30 PM

Hey, check this out by one of our forum's adminstrator, Borek.

http://www.chembuddy.com/?left=pH-calculation&right=toc

Title: Re: Calculating pH
Post by: SamstaUK on July 25, 2009, 08:23:29 AM

Okay one thing I'm not understanding is where the equilibrium numbers from from.

eg: [NO2]2
     -------- = 0.33
     [N2O4]

I have no idea how you get numbers from the letters? Is it based on RMM or something?

Title: Re: Calculating pH
Post by: Astrokel on July 25, 2009, 08:26:22 AM

Concentrations at equilibrium

Title: Re: Calculating pH
Post by: Borek on July 25, 2009, 11:03:05 AM

Quote from: SamstaUK on July 25, 2009, 08:23:29 AM

how you get numbers

Which numbers?

Title: Re: Calculating pH
Post by: SamstaUK on July 25, 2009, 11:05:19 AM

0.33

Title: Re: Calculating pH
Post by: Borek on July 25, 2009, 11:47:03 AM

This is equilibrium constant, in most cases these are measured experimentally and listed in tables.