greenyppols - 20-9-2005 at 07:07
oh well..I guess it's only a matter of time..a month after ordering some CaO thru an auction site, I complain and voilá, it comes in the mail,
whereupon I quit complaining. lol.
Except it ain't CaO. I would react with water and all it did was color the water cloudy, no heat, no nuthin'. I suspect its nothing useful,
probably ground chalk. Whats that, sodium carbonate, I think?
I wish I discovered this or tested before adding it to ethanol in an attempt for absolute ethanol..grr...
Im imagining I can just distill out the ethanol from whatever it was?? Stupid me....bah. People. May the crab lice gnaw at his investment portfolio.
BromicAcid - 20-9-2005 at 12:23
Are you aware of what calcium oxides properties are. Strictly speaking I haven't worked with calcium oxide before however from what I have read
it is actually somewhat insoluble and only hydrolyzes to a certain extent. Solutions of it (which don't contain much dissolved
Ca(OH)<sub>2</sub>
are known as lime water. So, dissolve as much as
you can in a small quantity of water and filter, then put a straw in it and blow into it, calcium carbonate should precipitate. If you think you got
calcium carbonate instead of the hydroxide from the seller, just add acid, there should be hardly any gas evolution (which would be distinctly
different then adding HCl directly to CaCO<sub>3</sub>.
garage chemist - 20-9-2005 at 12:41
Put a spoon of your presumed CaO in a test tube and add only a few drops of water. Only then the heat evolution is well observable!
Even the best CaO doesn't get hot if you add it to an excess of water.
Another possibility would be that you got calcium hydroxide instead of calcium oxide. Calciumhydroxide, a white powder looking almost exactly like
CaO, is widely available in the home stores here. It is made by slaking CaO with only a very little excess of water.
However, Calcium hydroxide loses its water at a much lower temperature than those at which CaCO3 loses its CO2.
Heating to 500°C for half an hour is already enough to turn Ca(OH)2 into CaO, I've tried it and the resulting dusty powder gets very hot when
water is added.
greenyppols - 20-9-2005 at 13:10
nope. It didnt do anything. Its supposed to make a great deal of heat when mixed with water and violently reactive with acid..
nadda on everything. Im pretty sure it aint what it was supposed to be...
According to the msds anyway..anyone know of a specific test? I was just winging it, but since it didnt react as expected...don't know what else
it is..
[Edited on 20-9-2005 by greenyppols]
garage chemist - 20-9-2005 at 13:32
Mix it into an excess of water and check the pH. If it's strongly alkaline, it's either calcium hydroxide or calcium oxide.
Add dilute acid and see if CO2 gets evolved. If yes, it's chalk (calcium carbonate).
Maybe it's calcium sulfate (plaster of paris)?
Mix it with water into a stiff dough and let it sit for a few hours and see if it gets hard.
12AX7 - 20-9-2005 at 13:38
Well let's see...
Reactive (as opposed to dead-burnt) lime, CaO, will absorb water, releasing some heat, as CaO + H2O = Ca(OH)2. Water has very high specific heat so
you must use very little to show this.
Ca(OH)2 shows an alkaline reaction in solution. Being slightly soluble as compared to the carbonate, it is able to form caustic solutions of alkalis
(Na2CO3 + Ca(OH)2 = 2NaOH + CaCO3).
CaCO3 is insoluble but reacts with acids: CaCO3 + H2SO4 + H2O = CaSO4.2H2O + CO2, CaCO3 + 2HCl = CaCl2 + H2O + CO2, etc., giving bubbles of CO2.
CaCl2 in solution can be detected by adding sulfate ions, which precipitates the nearly insoluble CaSO4.2H2O.
- If it bubbles with strong acid, it's the carbonate. It's calcium (or strontium, barium or lead) if it doesn't appear to dissolve in
H2SO4, or sulfate ions added to a solution cause a precipitate.
Tim
greenyppols - 21-9-2005 at 01:51
Thanks. Im going to check these tests later today...
Doh. I didnt even think of a PH meter that was laying around.
very little water..ok, maybe I used too much water, but wouldn't it have warmed up a little? I compared it to what I'd have expected from
KOH and some water, THAT made heat I felt, but maybe that was wrong guessing this? (Were I brave I would jam my pinkie finger in it to test for severe
burns, but Im a wimp)
lmfao @ paying for plaster of paris...boy the thought of that ticks me off, but still I have to laugh.
greenyppols - 21-9-2005 at 12:28
Ok..put a teaspoon of this stuff into test tube..added a few drops water. nothing. just soaked in a bit.
so I added a bit more water and dipped ph meter in..it came out 13.2.
Added some drain opener H2S04, about 6 'drips' off a glass rod, except for some slight 'psst' sound, nothing else came of it. No
bubbles if thats whats was supposed to happen, so that means its not the carbonate, right?
Im leaning towards calcium hydroxide... anyone else?
So let me ask, as I've already added about 75g to 1L of ethanol, it wont do any harm to it, right? I mean, I can distill out the ethanol from
whatever it is, and at least NOT having added any water to it? Maybe dried it even???? I dunno.
It wouldn't have converted to something wierd, would it??
Mumbles - 21-9-2005 at 14:46
Some calcium compounds form a complex with ethanol. I think this is possible with soluble salts in ethanol. Calcium hydroxide is not soluble in EtOH
to my knowledge. IT should be fine to filter and distill.