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A2 Chemistry pH questions

OK, I've been sat in the same position just staring at this question for 2 hours. Any help will be really appreciated, as I can't figure out how to solve this one problem:


Calculate the pH of a 0.0160 M KOH solution and estimate the pH of a 0.100 M KCl solution. Give your reasoning.
(at 25C, the value of Kw is 1.00 x 10^-14)

(i) pH of 0.0160 M KOH

I calculated this part already, got a pH of 12.2 for it.


(ii) pH of 0.100 M KCl

This is the part I'm struggling on, how do I go about making an estimate?



Thanks in advance
Reply 1
Essence™
OK, I've been sat in the same position just staring at this question for 2 hours. Any help will be really appreciated, as I can't figure out how to solve this one problem:


Calculate the pH of a 0.0160 M KOH solution and estimate the pH of a 0.100 M KCl solution. Give your reasoning.
(at 25C, the value of Kw is 1.00 x 10^-14)

(i) pH of 0.0160 M KOH

I calculated this part already, got a pH of 12.2 for it.


(ii) pH of 0.100 M KCl

This is the part I'm struggling on, how do I go about making an estimate?



Thanks in advance


Hi. for this question you have to take into account the parent acid and base of the salt. The K+ ion will have had been KOH and the Cl- would have been HCl hence a stong acid and base reaction to form the salt and water. The pH will be roughly neutral so about 7 as a stong parent acid and base react to release the same number of OH- and H+ ions in solution.

I think Kw was included as a hinter for this as equal OH- and H+ ions will be released in the reaction to form the salt and water thus the conc of each is the root of Kw which is 10*-7 hence pH 7.
Reply 2
Thanks! Good job, *positive rep*. Looks like this problem isn't that complicated after all, just a little logical thinking I guess.