About us | Feedback

Balancing redox equations

Balancing & stoichiometry

Reaction to balance & stoichiometry questions

Balancer and stoichiometry calculator

operating systems:
Windows 9x, 2000, XP, Vista, 7

single user license price:
€24.95 - approximately $33

Buy Now!

download 30-day free trial!
30-day money back guarantee!

Equation balancing & stoichiometry lectures » balancing redox reactions

» Equation balancing and stoichiometry calculator.

Redox reactions - in which charge is transferred between reagents - can be balanced by inspection, although it can be extremely difficult. But let's start with a very simple example:

Cu + Fe3+ -> Cu2+ + Fe2+

At first sight the equation seems to be already balanced, but if we check charges - it is not. There is +3 charge on the left, and +4 charge on the right, so we have to do something about it. Using the inspection method we should select the most complicated molecule first. Let's say it is Fe3+:

Cu + 1Fe3+ -> Cu2+ + Fe2+

If so, we can already add 1 in front of Fe2+:

Cu + 1Fe3+ -> Cu2+ + 1Fe2+

Trying to balance copper will lead us nowhere (atoms are balanced, but charges will be left unbalanced as they were from the beginning), so let's look at the charge - it can be balanced just like atoms. We have +3 on the left and +2 on the right - so we need additional +1 on the right side. Do you remember that we can use fractions at this stage? Half Cu2+ will do:

Cu + Fe3+ -> 1/2Cu2+ + 1Fe2+

What is wrong now is the left side of equation - too much copper at the moment. Once again, half will do:

1/2Cu + Fe3+ -> 1/2Cu2+ + 1Fe2+

Final touch - multiply everything by 2 to remove fractions:

Cu + 2Fe3+ -> Cu2+ + 2Fe2+

Atoms - balanced (one of copper and two of iron on both sides). Charge - balanced (+6 on both sides). We have just balanced the redox equation by using the inspection method. But in the case of more difficult ones - like this for example:

FeSO4 + KMnO4 +H2SO4 -> Fe2(SO4)3 + MnSO4 + H2O

this approach is a waste of time. Much easier and faster ways of balancing redox reactions are oxidation numbers method and half reaction method.

Questions? Comments? Feel free to discuss this page content at the chemistry quizzes forum (requires free registration).

AdSense

Chemical calculator software for pH calculation, concentration conversion solution preparation and chemical equation balancing chemical calculator