Is this right ?

2FeBr2+ 2H3PO4 --------(arrow) 2Fe(PO4)2 + 2HBr2

Is this right ?

2FeBr2+ 2H3PO4 --------(arrow) 2Fe(PO4)2 + 2HBr2


No. It's not right.

You need to Google the formulas of the compounds that you are using.

Note how the ionization takes place (center section). This can help you figure out how to balance the equation. Make sure the charge is balanced (same number of + as -). Note that hydrogen bromide is HBr. You will see an equal number of H+ and Br- in the middle section.

3 FeBr_2+ 2H_3PO_4 \,\rightleftharpoons\, 3Fe^{+2} + 6Br^- + 6H^+ + 2PO_4^{-3} \,\rightarrow\, Fe_3(PO_4)_2 + 6HBr

You didn't ask but there is also Iron(III) bromide: FeBr_3. That can also undergo a similar reaction:

FeBr_3+ H_3PO_4 \,\rightleftharpoons\, Fe^{+3} + 3Br^- + 3H^+ + PO_4^{-3} \,\rightarrow\, FePO_4 + 3HBr

Is that possible to write charges as 'sign' then 'number'? It's the first time I see that Perito... :confused:

Well, the thing to note here is that PO4 has a valency of 3, and not two. You can deduce that (if you didn't know) from the fact that Phosphoric acid has three atoms of hydrogen in one molecule. I'm convinced that if you had seen that, the reaction would have been good. :)

Is that possible to write charges as 'sign' then 'number'? It's the first time I see that Perito... :confused:


You mean like SO_4^{-2} instead of SO_4^{2-}?

When I was in school, we would write it the first way (on the left) with the sign first followed by a number. I've also seen it written the second way, but I don't do it that way.



I'm convinced that if you had seen that, the reaction would have been good.


... but for the HBr_2

Oh? OK, Perito. Here, we always write sulfate as SO_4 ^{2-}

Thanks! :)