Login

Welcome, Guest. Please login or register.

October 20, 2025, 07:02:08 pm

Author Topic: electrolysis  (Read 1111 times)  Share 

0 Members and 1 Guest are viewing this topic.

onlyfknhuman

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 372
  • Respect: +1
electrolysis
« on: November 03, 2008, 09:05:43 pm »
0
From the TSSM practice exam

English scientist, Sir Humphry Davy, first isolated potassium in 1807 by electrolysis of
molten potassium hydroxide.
a.
i. Write balanced half equations for the reactions that will occur at the anode and the
cathode in this cell.
anode __________________________________________________________
cathode __________________________________________________________

The Answer are

anode 4OH-(l) -> O2(g) + 2H2O(g) + 4e-
cathode K+(l) + e- -> K(l)

since its molten, were do they pull out water from? From Sir Humphry Davy's ass?

Much appreciated
English - VCD - Methods - Physics - Chemistry - Art - Japanese

give me the name list of all the hot chicks u know  ;)

unknown id

  • Victorian
  • Trendsetter
  • **
  • Posts: 131
  • Respect: +1
Re: electrolysis
« Reply #1 on: November 03, 2008, 09:06:58 pm »
0
the anode reaction is producing water, not consuming it.
VCE Outline:
2007:   Accounting [48]

2008:   English [44], Maths Methods [50], Specialist Maths [41], Chemistry [50], Physics [44]

ENTER: 99.70





Mao

  • CH41RMN
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 9181
  • Respect: +390
  • School: Kambrya College
  • School Grad Year: 2008
Re: electrolysis
« Reply #2 on: November 03, 2008, 09:13:19 pm »
0
and it's a gas when it's produced, so it escapes into the atmosphere [or is captured] and does not contribute to subsequent reaction
Editor for ATARNotes Chemistry study guides.

VCE 2008 | Monash BSc (Chem., Appl. Math.) 2009-2011 | UoM BScHon (Chem.) 2012 | UoM PhD (Chem.) 2013-2015

onlyfknhuman

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 372
  • Respect: +1
Re: electrolysis
« Reply #3 on: November 03, 2008, 09:22:36 pm »
0
ah crap, i see

wait, so why isnt the anode 2OH- +H2 -> 2H20[l] + 2e-

instead of 4OH-(l) -> O2(g) + 2H2O(g) + 4e-

is it because the water produced is a liquid? where as the answer is a gas.
English - VCD - Methods - Physics - Chemistry - Art - Japanese

give me the name list of all the hot chicks u know  ;)

Mao

  • CH41RMN
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 9181
  • Respect: +390
  • School: Kambrya College
  • School Grad Year: 2008
Re: electrolysis
« Reply #4 on: November 03, 2008, 09:33:20 pm »
0
no

it's because in the prior, you require H2 as a reactant, which you do not have.
Editor for ATARNotes Chemistry study guides.

VCE 2008 | Monash BSc (Chem., Appl. Math.) 2009-2011 | UoM BScHon (Chem.) 2012 | UoM PhD (Chem.) 2013-2015

onlyfknhuman

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 372
  • Respect: +1
Re: electrolysis
« Reply #5 on: November 03, 2008, 10:01:52 pm »
0
How do you know H2 is required? >_< sorry for being so stupid :S
English - VCD - Methods - Physics - Chemistry - Art - Japanese

give me the name list of all the hot chicks u know  ;)

cinnamonbun

  • Victorian
  • Trailblazer
  • *
  • Posts: 31
  • must remain sane for 6 more days...
  • Respect: 0
Re: electrolysis
« Reply #6 on: November 03, 2008, 10:18:08 pm »
0
because in the first one its 2OH- + H2
but you dont have any H2 so you know that cant be the reaction
therefore it has to be 4OH- -> O2 etc.
'07: Chinese, Physics
'08: Methods, Specialist, Biology, Chemistry, English
Desired Enter: 95+

onlyfknhuman

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 372
  • Respect: +1
Re: electrolysis
« Reply #7 on: November 03, 2008, 10:23:43 pm »
0
omfg im blind !!

thankss everyone
English - VCD - Methods - Physics - Chemistry - Art - Japanese

give me the name list of all the hot chicks u know  ;)