NEMO-Chemistry
International Hazard
Posts: 1559
Registered: 29-5-2016
Location: UK
Member Is Offline
Mood: No Mood
|
|
Calcium Chloride saga part 2
So to recap i spent days on the beach looking for oyster shells and cockle shells.
I then through increasing numbers into larger and larger buckets of 36% HCl. I ended up with a PH of around 2-3 and some shells undissolved.
I couldnt seem to get around this but dosnt matter. What i found in the end was a very fine pure white layer form on the bottom, along with general
organic crud.
My assumption being the solution became so saturated that the Calcium Chloride precipitated out.
Some of the crud is difficult to filter but turns out i dont have.
I have taken some of the liquid and boiled it for a while, i looked at wiki and it informs me Calcium chloride has a PH of around 8.1 for the hydrate.
On boiling a portion the beaker gave off a funny kind of odour, not exactly like HCl but pretty close and much weaker. Using litmus paper i discovered
after a while the PH had risen to around 8 (its not great paper).
The solution didnt crystallize but i may not have boiled long enough. My focus however is mainly on the solid, if i siphon the fine white powder off i
should be able to dry it in the microwave.
The liquid i will eventually boil down almost to dryness, but i got carried away and have nearly 20 ltrs of it!
I also have found a very cheap source of Calcium chloride :S. But i dont feel my time or acid was wasted, it has been good practice and interesting to
do, i got the acid cheap anyway.
I will try and form crystals and recrystallize it for practice, its likely i will use this stuff in my desiccator.
I also now own a kind of vacuum desiccator! Because i own alot of glass that isnt ground joints and need's bungs, i decided to get some RTV silicon.
The silicon isnt really the right one, i got the blue one by mistake and not the red heat/chemical resistant one. But what i did get with the kit i
got was a robust vacuum chamber made from stainless steel and very thick perspex.
I have some 'pallet wrap' which is like extra tough plastic film like you cover food with. So my idea is too line the vessel with this and use it as a
vac desiccator when i need one.
I am aware the double valve although stainless steel is likely to corrode as is the vac gauge, but they are cheap to replace and the container can be
heated with a bulb underneath should i want too.
I enjoyed the shell collecting although utterly uneconomical to do, it was a good learning curve, especially finding out the excess acid gasses off
before the solution boils and the Ph reached what i thought it should  .
Extra expensive Magnesium Sulphate from Magnesium Carbonate and sulphuric acid is next on the list. I will use drain acid for this as my decent
sulphuric acid source is drying up!!
With my exam money i will grab a couple of ltrs of the decent stuff before it become unobtainable!
Sodium hydroxide i got from a biodiesel place near to me, they sell it in 25Kg sacks pretty cheap, these i break down into 2 gallon sealed buckets.
So far the buckets are keeping it well! I know 25Kg is alot, but the price was similar to 5Kg on ebay! Also it gives me the option of making other
reagents and unblocking the drain lol.
I have some pics to get in the morning of the Calcium chloride and what happened in the end, the native pic format isnt postable so it takes some
messing with photoshop and then screen shots to get the pics online.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by NEMO-Chemistry  |
I couldnt seem to get around this but dosnt matter. What i found in the end was a very fine pure white layer form on the bottom, along with general
organic crud.
My assumption being the solution became so saturated that the Calcium Chloride precipitated out.
|
It's possible but shells aren't 100 % CaCO3. The insoluble residue may well be some siliceous matter.
|
|
|
NEMO-Chemistry
International Hazard
Posts: 1559
Registered: 29-5-2016
Location: UK
Member Is Offline
Mood: No Mood
|
|
Well eventually when i get it solidified and dried it will go away until i can 'analyse' it.
No particular reason but it would be cool to try and work out what is in it. I have a load more shells, so at some point i will try this again but do
it properly.
The one thing that made me think maybe some of the calcium chloride was depositing, was heat. When the lab is warmer the layer is a little less, and
when its colder the fine crud layer gets a fine white layer on.
So my wild guess was based on solubility with temperature, utter conjecture obviously. But for now speculation and conjecture will do while i learn
what is really going on, then i can look back and see how close i was (or not
 ).
I probably should read alot more before i do much, but trying things out is part of the fun, it kind of drives me wanting to read and learn.
At least i am getting past the throw it all in and see what happens stage! Now i am getting into the wanting to know what to expect first and working
out what happens.
My situation is i am going into S5 end of next week, In Scotland you start a new school year just before the end of the old one (yes strange system!).
I could in theory take National level 5 Chemistry at this stage, BUT the basics are taught in national level 4. So if i did decide to swap a subject
for chemistry i would have a mountain to climb to learn the basics taught in level 4.
I will see how much i can learn by next Thursday (i am not expecting miracles) but if i can learn enough to make me confident i can bring myself upto
speed and do the level 5 work, then i might try it.
It isnt such a huge gamble as i could drop Geography, so i dont have alot to loose by trying. The rest of the subjects i take i am doing 'Highers'
when i go back as i have just sat my national 5's.
But nothing to stop me doing another level 5, its just slightly unusual to drop a higher for a national 5. Some of my money my parents are giving me i
will spend on some decent basic books.
I am hunting ebay and abe books for bargains .
[Edited on 14-8-2016 by NEMO-Chemistry]
|
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
