Yesterday I found something interesting: <a
href="http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22Ca%28NO3%292%22+%224H2O%22+AND+%22Melting+point%22"
target="_blank">Ca(NO<sub>3</sub><sub>2</sub>·4H<sub>2</sub>O has a melting point of ~42°C!</a>
Could it be feasible to electrolyze it and get solid calcium metal?
[Edited on 9-14-2003 by blip]Mumbles - 14-9-2003 at 11:34
That is the point at which the water comes off of the molecule. What really happens is that the water comes off and dissolves the remaining Calcium
Nitrate. It will evaporate and you will be left with a less hydrated/anhydrous form of the molecule. The same thing happens with
MgSO<sub>4</sub>.7H<sub>2</sub>O. Even if you could electrolize this the Calcium metal formed would react with the water to
yield Calcium Oxide/Hydroxide and hydrogen gas.BromicAcid - 14-9-2003 at 17:59
The acutal melting point for anhydrous Ca(NO3)2 is 561 Cblip - 15-9-2003 at 13:37
I was hoping it wasn't too good to be true. BromicAcid - 19-6-2004 at 16:29
Just a passing thought. I've seen large amounts of CaH2 selling on eBay lately a Kg or so at a time very cheaply. My chemistry book confirms
what I thought, a somewhat low decomposition temperature, 675C reasonable by my standards. So why buy it in small amounts when you could pyrolyze
CaH2 and get it in reasonable amounts fairly cheaply?
Also, when I was researching production of the alkali earth metals for calcium it seems it is usually formed on an electrode barely touching the
surface of the molten salt melt and it is raised up slowly or slowly rotated to form a solid bar/sheet of Ca. This is done because if the electrode
is left in the melt the Ca thus formed is spongy and impure, but is it too impure for mad scientist use ?
By the way, what are the common melt constituents for calcium production? I only found a few, such as the 60 gram mol percent CaCl2, 20 gram mol
percent BaCl2, and 20 gram mol percent SrCl2 which gives calcium as 98% purity and although the Mp is 608C the cell is run at 675C.
Some of the original melts for calcium production also relied on eccentric mixtures formed between chlorides of the alkaline earths. And some used a
combination of calcium chloride and fluoride.
Interesting tidbit from the "Complete Treatise on Inorganic Chemistry"
Quote:
Calcium alone fuses at about 800, and ignites in air not far above this temp. There is, therefore, but a narrow range of temp. for the safe working
of the electrolytic process. The molten metal also readily forms a metal fog.
Also I've read that aluminum does not work well at all to reduce calcium oxide for calcium production, however it works very well for producing
strontium and barium.
For the preparation of calcium by electrolysis on the lab scale my book referred me to:
O. Ruff and W. Plato, Ber. dtsch. chem. Ges. 35, 3612 (1903); W. Muthmann, H. Hofer and L. Weiss, Liebigs Ann. Chem. 320, 231 (1902); B.
Neumann and E. Bergve, Z. Elektrochem. 20, 187 (1914); M. Trautz, ibid. 21, 130 (1915).
And I know I saw somewhere on this site the reduction of CaCl2 with Al mentioned. I could see this being favored in that the AlCl3 formed would be
volitile but has anyone tried this?Proteios - 20-6-2004 at 08:30
im going from memory again here..... if you mix the solids CaNO3.4H2O and NH4NO3..... the stuff forms a liquid.... very runny but technically a
glass...... still kinda funny though... mixing two 'ionic solids' and watching it form a liquid!vulture - 21-6-2004 at 04:49
Quote:
The acutal melting point for anhydrous Ca(NO3)2 is 561 C
Won't it decompose long before that temperature has been reached?
<sub>2</sub>·4H<sub>2</sub>O has a melting point of ~42°C!</a>