are (H2o)9 and 9(H2o) the same thing ?
No, (H2O)9 and 9(H2O) are not the same thing. The placement of the number outside or inside the parentheses indicates a different interpretation.
(H2O)9 means that there are 9 water molecules grouped together. So, it represents a cluster of 9 water molecules bonded together.
On the other hand, 9(H2O) means there are 9 clusters of water molecules. It indicates that there are nine separate groups, each consisting of one water molecule.
The difference in placement of the number outside or inside the parentheses changes the meaning and structure of the chemical formula.