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I want to create saturated coper(II) sulfate solution in order to grow crystals. Is boiling a solution of copper sulfate at home safe? Are there any risks? Is the vapour pure water?

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  • $\begingroup$ It is safe. I have done it quite often. The vapor is pure water. It is difficult get nice crystals. $\endgroup$
    – Maurice
    Commented Feb 19, 2022 at 21:30
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    $\begingroup$ It will be hot, do not touch it. $\endgroup$ Commented Feb 20, 2022 at 1:20
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    $\begingroup$ One aspect of knowing what you're doing is knowing the properties relevant to your process, such as the compound you want may not be fully stable at the boiling point of water (or whatever solvent you're boiling off). Here, boiling is not best after all. See the answers below. $\endgroup$ Commented Feb 20, 2022 at 11:25

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While the hazard associated with boiling copper sulfate solution is minimal (there can be fine aerosols of the solution carried by the bubbles during a vigorous boiling), the chemistry must be respected. To get beautiful blue crystals of the pentahydrate you may want to evaporate the solution at lower temperature (and thus more slowly) than boiling the solution. From Wikipedia:

Copper(II) sulfate pentahydrate decomposes before melting. It loses two water molecules upon heating at 63 °C (145 °F), followed by two more at 109 °C (228 °F) and the final water molecule at 200 °C (392 °F).[1][2]

Cited References

1. Andrew Knox Galwey; Michael E. Green (1999). Thermal decomposition of ionic solids. Elsevier. pp. 228–229. ISBN 978-0-444-82437-0.

2. Wiberg, Egon; Nils Wiberg; Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. p. 1263. ISBN 978-0-12-352651-9.

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