|MadSci Network: Chemistry|
Diamond does not dissolve in water for two reasons. First, it is a pure crystal with covalently bonded carbons. The energy required to break these tetrahedrally oriented carbon-carbon bonds is far greater than any energy released by solvation. NaCl has ionic bonding outside water, which can dissociate. Dissociation is more likely here because it is very polar (electronegative chlorine). Conversely, the carbon-carbon bonds share the electrons more equitably and no stability is gained through solvation in water. Second, even if diamond could dissolve (weak bonds) it wouldn't dissolve in water. It would be in an organic compound like hexane because, after all, diamond is organic (made of carbon).
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