[mememehere]

Is it necessary? The equ is it all abt writing the number of electrons gained/loss?

[cliverlong]

Interesting question. I had a little look around and my guess is that one adds state symbols if at least one species changes state.   

Clive

[Borek]

There are no fixed rules for that (on exams you better ask whether you are expected to put them or not). IMHO as long as the there is no risk of ambiguity you may omit state symbols.

[mememehere]

 

[cliverlong]

There are no fixed rules for that (on exams you better ask whether you are expected to put them or not). IMHO as long as the there is no risk of ambiguity you may omit state symbols.

Jim Clarke doesn't use state symbols
http://www.chemguide.co.uk/inorganic/redox/equations.html

Mark Bishop does
http://www.mpcfaculty.net/mark_bishop/Redox_balancing.htm

The following examples do sometimes and sometimes not in the same equation !
http://www.chemistry.co.nz/redox_new.htm

Wikipedia examples here do use state symbols:
http://en.wikipedia.org/wiki/Redox#Balancing_redox_reactions

http://www.xenware.net/ancq/1569/FOUR-30.pdf
does see page 2 for examples.

As I wrote before, and as in the examples if you look at them, the "rule", or at least pattern, seems to be put in state symbols when the state of any species changes in the reaciton.

This may be an author preference and there may be no IUPAC standard about half-equations (except one can only add electrons, not subtract them.)

Beyond the googling I have done on this question I don't have a definitive answer - if you are looking for one. I suspect there isn't the definitive answer that you desire. I may be wrong.

If I was to put money on it - I would trust Borek's opinion.

Best wishes,

Clive