Text above the double arrow (harpoons)

[Sigrid Kronenberger]

Hi there, 

I've started to write an protocol about my chemical practical training
with LyX. I'm using version 1.3.5 on Mandriva Linux 2006. 

I need to insert different chemical equations, everything works well,
there's only one exception: 

I need to write a formula above the double arrow (exact:
\rightleftharpoons), that should look similar to this: 

           CuSO4
Zn + 2HCl  <--->  ZnCl + H2 

Is there a way, how I can do this? I've tried already to use a matrix,
but then the text is too big compared with the arrow or the space
between the arrow and the text is too big. 

Any ideas? I appreciate your help. 

Thanks. 


Sigrid


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Thanks.