November 27, 2024, 11:39:06 AM
Forum Rules: Read This Before Posting


Topic: Redox equation help please  (Read 4269 times)

0 Members and 1 Guest are viewing this topic.

Offline murrayt6

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Redox equation help please
« on: May 30, 2007, 08:41:23 AM »
I did a search first, but I'm still having trouble with this and any help would be greatly appreciated:

In the redox equation: 2MnO4,- + 5H2SO3  -->  2Mn,2+ + 3H2O + 5SO4,2- + 4H+ what is the change in the oxidation number of the element that is reduced? Enter your answer as a number with the correct sign, for example, -3 or +2.

On the left side, 2Mn04-: Mn is +7 to balance O(-2x4) -1.
                       5H2SO3: (H2 is +2), (O is -6), so (S must be +4)

On the products side
(I think this is where I run : should 2Mn, 2+ be 0 since it is by itself or should it be +2?
into trouble)                    3H2O: (H2 is a +2), (O is a -2)
                                    5S04 2-: (0 is -8), then with 2-, S must be +6
                                    4H+:H is a +1 but here is it a +2 because of the + after it?

I'm just getting really frustrated and I know I'm probably making it more difficult than it really is, but I need to know the oxidation # of the element that is reduced.  Thanks for taking the time to help out. :-\

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27862
  • Mole Snacks: +1813/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Redox equation help please
« Reply #1 on: May 30, 2007, 09:04:25 AM »
Read how to assign oxidation numbers, especially in the case of charged mono atomic ions.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline qwerty44

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Re: Redox equation help please
« Reply #2 on: June 17, 2007, 08:12:02 PM »
Mn would go from +7 to +2 (because Mn2+ has a charge). So I think the reduction would be -5.

Sponsored Links