Balance the following half-reactions.
(a) (acidic) Cr2O22-(aq) -...

Question

Balance the following half-reactions. 
(a) (acidic) Cr2O22-(aq) -> Cr3+(aq)

Accepted Answer

Hi everyone. So you're asking about the balance have reactions under basic conditions and identify whether it is an oxidation or reduction reaction. We need to first write this out. We have video two plus years. It's gonna give us B. O two plus one. Now we need to balance the non hydrogen and non oxygen elements first. And as you can see this is already balanced. So the next thing we need to do is balance the oxygen by adding H20 liquid. To decide that needs oxygen. You have to auction on the reaction side. Put one on the product side so we can add one H 20 liquid. And then we have two options on the product side. Now I need to balance our hydrogen by adding H plus the side that needs hydrogen. We have no hydrogen on the right hand side we have two on the product side. We can add two h plus on the reacting side, dynamic imbalance are charges by adding the electrons to the more positive side. If you look at our charges plus two here plus one here plus two and zero we're gonna have overall charge of plus three Over here Plus two over here we need to add electrons to the reacting side. We're gonna add one electron. So now we're gonna balance any remaining H plus by adding an equal amount of O. H minus ions to both sides. You have to age plus on the right hand side but none on the private side. We need to add 20 H minus to both sides. We're gonna get the L two plus equals Plus two H plus plus one electron plus two O H minus. It's going to be L two plus. Like what Plus H 2 0. Liquid. That's 20. H minus. Hey chris. And so now that H plus and the O H minus will combine to form H +20 liquid. You're gonna get bl two plus a quiz plus two H +20 liquid plus one electron, Michelle's VL two plus Quinn plus H +20 liquid plus two O H minus. So now we can cancel our common species. We have two H two over on the raft inside. But one on the product side we're gonna be left at one H on the inside. So far. Our balanced reaction. V O two plus Plus H 20. Quinn Plus one electron. And it shows v. O. In class Plus 20. H. Finance for our oxidation reaction. This means we're losing electrons that the electrons gonna be on the product side. And for the reduction reaction we're gaining electrons to the electron is going to be on the wrapped inside. But in this case this is a reduction reaction. You have electrons on the left side. We're gaining electrons. Thanks for watching my video and I hope it was helpful

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