Please see the following figure. This is from the high school chemistry book of my son. He wants to know what does that /2 after $\ce{-COOCa}$ mean.

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The book is a non English one. And I have changed the relevant caption to English.

Primary searches over Google have not revealed anything usable. And my major not being Chemistry might have to do something with this.


1 Answer 1


It means half of calcium.

The organic acid is $\rm{COO}^-$, whereas calcium is $\rm{Ca}^{2+}$. For the structure to be fully correct, there are two benzoic acids per one calcium. Other way round this would be $\rm{(C_6H_5COO)_2Ca}$. Full drawing of this will be way to messy, so it is simpler to put half calcium to one acid.


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