6B.9

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Xuan Kuang 2L
Posts: 31
Joined: Wed Nov 14, 2018 12:23 am

6B.9

Postby Xuan Kuang 2L » Thu Jan 24, 2019 2:30 pm

6B.9
a) Complete the following table
[H3O+] [OH-] pH pOH
i) 1.50 mol.L-1
ii) 1.50 mol.L-1
iii) 0.75
iv) 0.75

b) Rank the four solutions in order of increasing acidity

(I understand iii) and iv), but I am not sure why I keep getting i) and ii) wrong. When I calculate for i), I get [OH-]= 6.67x10^-15 mol.L-1, pH= -0.176, and pOH= 14.176, and similar answers for ii), but these do not match the answer key, which says for i), [OH-]= 1.50x10-14, pH= 0.176, and pOH= 13.824. Could someone help me solve this? Thanks in advance :D)

Philip Lee 1L
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: 6B.9

Postby Philip Lee 1L » Thu Jan 24, 2019 5:31 pm

I think I got similar answers to what you got. I believe that the answer given in the back is a typo.

Textbook answer for (i):
[H3O+] = 1.50
[OH-] = 1.50 x 10-14

[H3O+] x [OH-] should be equal to 1.0 x 10-14
1.50 x 1.50 x 10-14 clearly does not equal 1.0 x 10-14


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