December 05, 2021, 10:14:04 AM
Forum Rules: Read This Before Posting


Topic: Balance of redox reaction  (Read 303 times)

0 Members and 1 Guest are viewing this topic.

Offline Glitch000

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Balance of redox reaction
« on: November 17, 2021, 09:16:43 AM »
hi, i can't resolve this redox reaction, can someone help to find the error?

P4O6 + I2 = P2I4 + P4O10

first i found the oxidation number and then i wrote the semi reaction and I balanced them:

Red1:   12H+ + 4e- + P4O6 = 4P+2 + 6H2O
Red2:   4e- + 2I2 = 4I-

Then i added them toghether:
12H+ + 8e- + P4O6 + 2I2 = 4P+2 + 6H2O + 4I-

Ox: 4H2O + P4O6 = P4O10 + 8e- + 8H+

The total arrives:
12H+ + 8e- + P4O6 + 2I2 + 4H2O + P4O6 = 4P+2 + 6H2O + 4I- + P4O10 + 8e- +8H+

at the end my balanced reaction arrives:
2P4O6 + 2I2 + 4H+ = 4P2I4 + P4O10 + 2H2O

The reaction is wrong because the exact balanced reaction is this:
5P4O6 + 8I2 = 4P2I4 + 3P4O10

I don't understand were is my error... ???


Online Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26865
  • Mole Snacks: +1742/-403
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Balance of redox reaction
« Reply #1 on: November 17, 2021, 11:07:32 AM »
Wow. Just wow. I would never think it is possible to overcomplicate thing by that much. Try to balance just by inspection (most likely starting with iodine will be the easiest approach).

But:

Red1:   12H+ + 4e- + P4O6 = 4P+2 + 6H2O
Red2:   4e- + 2I2 = 4I-

Then i added them toghether:
12H+ + 8e- + P4O6 + 2I2 = 4P+2 + 6H2O + 4I-

This is already wrong - when you add these two reactions you assume they occur in some particular ratio. Why?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Orcio_Dojek

  • Full Member
  • ****
  • Posts: 354
  • Mole Snacks: +33/-3
Re: Balance of redox reaction
« Reply #2 on: November 17, 2021, 11:13:35 AM »
Quote
at the end my balanced reaction arrives:
2 P4O6 + 2 I2 + 4 H+ = 4 P2I4 + P4O10 + 2 H2O
Of course its wrong. Did you ever read what have you written here ?

Where is the error:
Quote
Red1:   12 H+ + 4 e- + P4O6 = 4 P2+ + 6 H2O
Red2:   4 e- + 2 I2 = 4 I-

Then i added them toghether:
12 H+ + 8 e- + P4O6 + 2 I2 = 4 P2+ + 6 H2O + 4 I-

Formula of the compound is the P2I4, not P2I22+ as you have written (4 P2+ + 4 I-) (Red2 needs to be multiplied by 2).
« Last Edit: November 17, 2021, 01:19:18 PM by Orcio_Dojek »

Sponsored Links