Clarification on example

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Clarification on example

Postby 205150314 » Sun Jan 26, 2020 9:42 pm

Can someone please clarify an example professor Lavelle gave once about 1*10^-11 M HCl not creating that much concentration of H3O+ and then stating that H2O has 1*10^-7 [] of H3O+? I didn't write down everything and now its kind of confusing me.

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Re: Clarification on example

Postby stephaniekim2K » Sun Jan 26, 2020 10:04 pm

pH is equal to the -log[H3o+] so the lower the concentration of [H3O], the smaller the pH, meaning it is a strong acid. Since the pH of H2O is 7, neutral, [H3O]=107.

Angus Wu_4G
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Re: Clarification on example

Postby Angus Wu_4G » Sun Jan 26, 2020 11:39 pm

Lavelle gave that extra example in class, because if you had calculated the pH of 1X10^-11 M HCl, you would actually get a pH of greater than 7, which is incorrect since an acid will not make the solution more basic. Essentially, your acid is so diluted that it is negligible, and that you have to remember to factor in the H30+ concentration that is already in water. If you added the concentrations and computed the new pH, you would get a pH of 7, or slightly less than 7.

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