Time remaining:
What is the pH of a solution saturated with quinhydrone if the potential of a platinum electrode in

label Chemistry
account_circle Unassigned
schedule 1 Day
account_balance_wallet $5

What is the pH of a solution saturated with quinhydrone if the potential of a platinum electrode  in the solution, measured against a saturated calomel electrode, is −0.205 V?

Dec 9th, 2014

The electrode reaction is 

C6H4O2 + 2H+ + 2e- → C6H4(OH)2

Quinone is oxidant, and hydroquinone is reductant.

For the potentiometric measurements, it is a combination of the quinhydrone electrode with suitable reference electrode to create electrochemical cell. Thus,

pH = (E0(Q/H2Q) – Ecalomel – E) / 2.303 RT/F

E0(Q/H2Q) = 0.699 V

E calomel is a standard table data that was supposed to be given to you in a problem conditions along with the Temperature. I suppose it is room T conditions or that would be stated otherwise. Thus, E calomel at T room = 0.2410 V

E is measured = - 0.205 V

T = 25 C

R = 8.314 J kmol-

F = 96485 C mol-

Plugging in numbers: pH = (0.699 V - 0.2410 V + 0.205 V) / 0.05916 V =  0.663 / 0.05916 = 11.2

Wasn't easy problem, huh? :)

Hope it helps!


Dec 18th, 2014

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.
Click to visit
The Notebank
...
Dec 9th, 2014
...
Dec 9th, 2014
Jun 25th, 2017
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer