# Pyrolysis of calcium chloride dihydrate

Does the pyrolysis of $$\ce{CaCl2 · 2 H2O}$$ give $$\ce{CaCl2 + 2 H2O}$$ or $$\ce{Ca(OH)2 + 2 HCl}?$$

• What temperatures are we talking about? – andselisk Dec 11 '19 at 8:09
• Ordinary heating – Just A Young Artist Dec 11 '19 at 8:22
• I did synthesis of uranium tungstates for quite some time and was imprinted to me that "ordinary heating" is supposed to be 900–1100 °C. An organic chemist would probably understand "ordinary heating" as some elevated temperature around the boiling point of water. So, again, what temperatures are we talking about? – andselisk Dec 11 '19 at 8:26
• About the boiling point of H2O – Just A Young Artist Dec 11 '19 at 8:28
• @andselisk Actually, I think I would consider ordinary heating reflux for whatever the solvent is. Which can go down to room temperature for ether or DCM ;) – Jan Dec 11 '19 at 8:58

All calcium chloride hydrates give away water of crystallization upon heating without forming a hydroxide, and the anhydrous $$\ce{CaCl2}$$ melts without decomposition [1, p. 162]:
$$\ce{CaCl2 · x H2O ->[\pu{260 °C}] CaCl2 + x H2O}$$