I'm trying to understand the difference in properties between water in crystals in different positions in the lattice. In this wikipedia article It quotes:

Both notations can be combined as for example in copper(II) sulfate: $\ce{[Cu(H_2O)_4]SO_4 · H_2O}$

referring to water which is coordinately bonded to the copper and water which is in the crystal structure left over.

Firstly, is this the same as: $\ce{CuSO_4 · 5H_2O}$ ?

And secondly, would there be a difference in how the water acted upon heating? Would it only be the one water in the lattice structure that left or all 5 waters? i.e.

$$\ce{[Cu(H_2O)_4]SO_4 · H_2O ->[heat] [Cu(H_2O)_4]SO_4 + H_2O}$$


$$\ce{[Cu(H_2O)_4]SO_4 · H_2O ->[heat] CuSO_4 + 5H_2O}$$

  • 2
    $\begingroup$ Yes, both are the same thing. As for the second part, there is no simple rule what water molecules are eliminated first upon heating and an experiment may show unintuitive results, for instance, for copper(II) sulfate looses four water molecules first, not one (see Hydrate decomposition equation steps). $\endgroup$ – andselisk Apr 12 '19 at 17:24

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