Why is the equation for a sodium-sulfur battery reaction considered 'not right'?

[Creaturemagic]

2Na + 3S --> Na2 + S3^2-

Homework Statement

So I have the equation 2Na + 3S --> Na2 + S3^2- (the 2- being the charge of S3)
This is the reaction generated in a sodium-sulfur battery.
And all's good there, I can see there are two electrons transferred in the reaction and I know it's a redox reaction. However when I handed in my draft for this piece of assessment, I got it back with the comment that this reaction didn't look 'right'.

The task at hand is to summarise an article (Mine being on Electric Cars) and then write four 'focus' questions and model answers. So the reaction is taken straight from the article and I just don't see how it isn't right.

Thanks for any help clearing this up, I plan to ask my teacher tomorrow, so I'll keep this updated.

 

[chemisttree]

If you mean 2Na + 3S <----> Na₂S₃,
then you have it right.

http://books.google.com/books?id=VIFnWIBq_wUC&pg=PA7&lpg=PP1&output=html_text

 

[Borek]

Or change Na₂ to 2Na⁺...

 

[epenguin]

It could well not look right because that is not everyday chemistry - you will have seen it works in quite hairy conditions not to be reproduced in a school laboratory.

I don't know anything but looking at this http://en.wikipedia.org/wiki/Sodium–sulfur_battery and the book extract it looks like it's a mix of polysulfides all the way down and even further than S₃^2- so, as they say it's a bit of a convention to fix on S₃^2-. I expect you can get some S₂^2- and S^2-, perhaps they are not wanted.