Test 1 Practice Worksheet #5

Moderators: Chem_Mod, Chem_Admin

Emily Vainberg 1D
Posts: 102
Joined: Sat Jul 20, 2019 12:15 am

Test 1 Practice Worksheet #5

Postby Emily Vainberg 1D » Tue Jan 21, 2020 2:54 pm

Question 5 states: What is the pH of a .030 M solution of NaC6H7O2? The pKa of C6H8O2 is 4.76. C6H7O2-(aq) + H2O(l) ⇔ C6H8O2(aq) + OH-(aq)


For my answer I got the pH= 10.858
Did anyone else do this problem and get the same answer?

nicolely2F
Posts: 149
Joined: Sat Sep 14, 2019 12:17 am

Re: Test 1 Practice Worksheet #5

Postby nicolely2F » Tue Jan 21, 2020 6:17 pm

Yes, I got 10.86

Jessica Li 4F
Posts: 115
Joined: Fri Aug 09, 2019 12:16 am

Re: Test 1 Practice Worksheet #5

Postby Jessica Li 4F » Wed Jan 22, 2020 10:29 pm

I actually got 8.6 - I think you forgot to convert the given pKa value to pKb, as the molecule you are dealing with is actually the base.

Luc Zelissen 1K
Posts: 57
Joined: Mon Jun 17, 2019 7:23 am

Re: Test 1 Practice Worksheet #5

Postby Luc Zelissen 1K » Wed Jan 22, 2020 10:39 pm

Jessica Li 4F wrote:I actually got 8.6 - I think you forgot to convert the given pKa value to pKb, as the molecule you are dealing with is actually the base.

I got the same answer as you!

Sally Qiu 2E
Posts: 105
Joined: Fri Aug 30, 2019 12:18 am

Re: Test 1 Practice Worksheet #5

Postby Sally Qiu 2E » Wed Jan 22, 2020 11:12 pm

i got 8.62

Junwei Sun 4I
Posts: 125
Joined: Wed Oct 02, 2019 12:16 am

Re: Test 1 Practice Worksheet #5

Postby Junwei Sun 4I » Thu Jan 23, 2020 12:15 am

I got 8.62 too maybe you forget to convert pKa to pKb since C6H7O2-(aq) is a base. And you first calculate pOH and then subtract and get the pH value.

Emma Popescu 1L
Posts: 105
Joined: Wed Sep 11, 2019 12:16 am

Re: Test 1 Practice Worksheet #5

Postby Emma Popescu 1L » Fri Jan 24, 2020 2:02 pm

I also got 8.62. You have to convert pKa to pKb


Return to “Equilibrium Constants & Calculating Concentrations”

Who is online

Users browsing this forum: No registered users and 1 guest