[otrivine]

hi i am really stuck on balacing the equations like
FeO4 2- + h+ gives Fe3+ + 02 + H20

how would you balance it please someone show me the step really confused

[Killjoy-]

You'd need to conserve charge and also ensure you have the same atoms on each side.

As it stands you have a net charge of -1 on the LHS and a net charge of +3 on the RHS.
You also have four oxygens and one hydrogen on the LHS and three oxygens and two hydrogen atoms on the RHS.

I started by trying to balance the charge - 5 lots of H+ would work if we had 5/2 lots of water on the RHS.
(Note we haven't dealt with the oxygen yet.)

Double everything and you end up with

2FeO₄^2- + 10H⁺ --> 2Fe³⁺ + 2O₂ + 5H₂O

Charge is conserved but we still need to deal with oxygen:
LHS we have 8 oxygens, RHS we have 9 oxygens.

If we change the no. of O₂ everything else will still be balanced, so replace 2 with 1.5 before the O₂.

Double everything (again) to end up with whole numbers.

The trick here was to notice that manipulating the number before O₂ retained the same charge and left all the other atoms as they were.

[otrivine]

(Original post by Killjoy-)
You'd need to conserve charge and also ensure you have the same atoms on each side.

As it stands you have a net charge of -1 on the LHS and a net charge of +3 on the RHS.
You also have four oxygens and one hydrogen on the LHS and three oxygens and two hydrogen atoms on the RHS.

I started by trying to balance the charge - 5 lots of H+ would work if we had 5/2 lots of water on the RHS.
(Note we haven't dealt with the oxygen yet.)

Double everything and you end up with

2FeO₄^2- + 10H⁺ --> 2Fe³⁺ + 2O₂ + 5H₂O

Charge is conserved but we still need to deal with oxygen:
LHS we have 8 oxygens, RHS we have 9 oxygens.

If we change the no. of O₂ everything else will still be balanced, so replace 2 with 1.5 before the O₂.

Double everything (again) to end up with whole numbers.

The trick here was to notice that manipulating the number before O₂ retained the same charge and left all the other atoms as they were.

Does this rule work for everything

[Killjoy-]

(Original post by otrivine)
Does this rule work for everything

I do these by inspection. Usually they aren't too difficult so it isn't a problem.

If you knew the half-equations it would be simple - just eliminate the electrons!

I think it helps to start by balancing a species that appears in only one reactant and product, but I doubt my reasoning would work for every question.