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CHRIS25
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Olive oil and KOH
Would someone be kind enough to explain to me what I am looking at please?
I have mixed 100g virgin olive oil with 20g KOH in 44.5mLs de-ionized water. This is for the first of two processes to extract oleic acid.
I see three distinct layers in this beaker which holds 150mLs soln and is 5cm depth total. I do not understand these layers nor which one contains
the potassium oleate?
Bottom layer is 1cm depth and is a nice clear orange
Middle layer is 0.5cm deep and is a creamy off-white precipitate
top layer is 3.5cm depth and is a non-transparent milky orange.
This is my first ever experiment with fatty acids and touching organic chemistry which I am ignorant about despite having done some preparatory
reading. So thankyou for your help.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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I have never prepared potassium soaps from olive oil, but usually when soap making, I blend the hydroxide solution with the oil with a blender
until it starts to thicken (known in soap making as trace). At this point you can pour it out into a tub to allow it to react further.
When you hit trace, usually the soap sets into a off white mass pretty quickly in my experience.
Not sure why you are seeing layers at this stage... maybe you're not blending it? It's essential to blend it until it starts to thicken because the
potassium hydroxide solution will not want to mix with the oil, but by blending you get miniscule droplets of it forming in suspension which greatly
increases the surface area for reaction between the two phases and allows the reaction to start causing it to stiffen up and lock the micro-droplets
in place.
Just how long one needs to blend varies widely and depends mainly on the temperature of the blend, the type of oil and the concentration of the
caustic solution and nature of the blender, but don't be surprised if it takes a few minutes. Don't leave it unattended though when blending because
when it starts to thicken at trace, it will thicken rapidly thereafter that can burn out a blender if you don't turn it off!
In the hot method of making soap (fastest method), one can leave the soap in a slow cooker for a few hours to react further/completely after
achieving trace using a blender, in the cold method it takes much longer (sometimes days).
A handheld blender works very nicely for reaching trace... but be warned, wear old clothes, rubber gloves and eye goggles and work outside
because of the possibility of spatter of very caustic, viscous and sometimes hot material that burns like hell! Bad caustic burns are very painful and
take long to heal.
In cold soap making, the soap is usually cured for several weeks after cutting into blocks, but this is not necessary in your case as you would
probably not mind the presence of small amounts of potassium hydroxide as you will be neutralising/acidifying everything with HCl afterwards anyhow to
get your oleic acid.
Finally, if you're wondering what trace looks like, it's kind of the consistency of soft margarine.
Hell I'm probably going into way to much detail here, my apologies if so!
[Edited on 7-4-2014 by deltaH]
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CHRIS25
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Oh, no I did not blend it, just stirred it two or three times and then sat down. Thought that the potassium oleate would be there to filter off -
simply did not understand this at all. thankyou for your help, so I presume that once I have blended it I need to wait a few weeks before mixing with
the acid? Or can I begin the second phase after blending, which seems logical at this moment but I could be wrong?
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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At trace, the saponification reaction has only just started (hence the name). Thereafter you have two choices, if you're in a hurry, pop it
in a slow cooker and leave it for a few hours (several?). When it's done, you should have a solid mass of off white soap (colour varies depending on
oils used so don't worry if this looks slightly beige or whatever, the point is it should resemble a solid mass of... well soap The second choice is the 'cold method' which entails pouring out the trace soap into
a mould, waiting overnight for it to set, then cutting it into blocks and waiting a few days for saponification to complete at room temperature.
If you intend using your soap for bathing (you may well want to when you start making these), please do leave it for several weeks to cure once cut
into soap sized blocks and placed on a rack. This is to ensure that small amounts of potassium hydroxide remaining react with CO2 to
make potassium carbonate and also to dry the block. Else you will have a very harsh soap that will wrinkly your skin quickly and even burn/peel it!
Whatever the case, do not proceed to stage two until you have a hard mass of soap, either by using a slow cooker or letting the blocks sit for a few
days in the cold method.
[Edited on 7-4-2014 by deltaH]
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CHRIS25
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Ok then Thankyou very much. I only need to do this for oleic acid and not for bathing, I used ratios of KOH to olive oil allowing a 3% more KOH,
which is not recommended for soap making, they usually say a bout 5% less than the SAP chart calculations, anyway, I thank you for your help here.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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My pleasure CHRIS25. Please post some pics of your stage one, I'm curious to see what a potassium olive oil soap looks like. Also, a
photo of the trace stage may be useful for others attempting the same. BTW, olive oil soaps are also known as Castile soap after the region in Spain
where they were origionally made.
[Edited on 7-4-2014 by deltaH]
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CHRIS25
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Glad to be of some use. This is literally a minute after blending. Will post image after 24 hours. should add I blended till the top layer looked
like speckles were dripping from the blender blade, this took about 6 minutes at top speed.
![IMG_1332.JPG - 323kB](http://www.sciencemadness.org/talk/files.php?pid=326212&aid=30837)
[Edited on 7-4-2014 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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Thanks! You're on your way...
It's hard to tell from the photo, but it looks like you're still a little shy of a good trace, but if it's firming up homogeneously, then you're set
(excuse the pun).
If you're going the cold route, I'd wait a few days before doing your stage two just to ensure saponification has run it's course, but you should have
a firm block by tomorrow already.
[Edited on 7-4-2014 by deltaH]
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macckone
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One note is that potassium based soaps are usually liquid. It generally won't set like a sodium based soap. Since you are trying to separate the raw
acid, then you should really use the sodium hydroxide because the potassium base soap won't separate the glycerine like sodium hydroxide will. You
can separate it but it will be difficult.
*added link*
ps. The following link is a good tutorial on liquid soap. Notice there is no step for separating the glycerine. You need a solid soap for that
although in theory you can separate the glycerine in practice it isn't practical. Once you have pure soap then you would back titrate with acid to
give the oleic acid.
http://chickensintheroad.com/house/crafts/how-to-make-liquid...
[Edited on 7-4-2014 by macckone]
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deltaH
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macckone, when making liquid potassium soaps, does one not nevertheless need to add quite a bit of water to make it liquid as I
recall? I think the amounts op used should result in a firmish soap.
Secondly, the residual glycerine should not be a problem, because in stage two, he's going to dissolve this up in hydrochloric acid and the glycerine
'should' simply go in the aqueous phase together with the water and KCl.
If the potassium soap doesn't come out rock hard, that's a bonus because he still needs to dissolve it into the acid in phase two of his process.
[Edited on 7-4-2014 by deltaH]
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CHRIS25
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Thankyou Nicola, it is already firm. macckone, the tutorial is very well presented. A good link. I take your point about Sodium and Potassium and
actually only chose the potassium hydroxide because it is lab grade, whereas my sodium hydroxide is commercial. That was the only reason, but I take
your point if I have to do this again which I probably will.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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Best of luck CHRIS25 and keep the photos coming, I love them!
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CHRIS25
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Well you are going to love this one, any hard to remove stains?
After two hours it had eaten away at my otherwise very strong plastic container.
![IMG_1333.JPG - 152kB](http://www.sciencemadness.org/talk/files.php?pid=326248&aid=30839)
also read a whole list of plastics with names I can not pronounce that are resistant to KOH plus a whole list that are not resistant. But now it's
eating its way through a new york pizza box! Time for damage control.
[Edited on 7-4-2014 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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HoH
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Generally speaking, KOH is the hydroxide for liquid castile soap. NaOH is used for making bar soap.
A good recipe for organic liquid castile soap (I made 2 gallons of the stuff last week).
-In a stone or glass pot, 6oz of Vegetable glycerine is heated to 200f at which point 3oz of KOH is stirred in. An exothermic reaction occurs and 95%
of the KOH goes into solution.
-In a separate pot, 13oz of olive oil, 1.5oz of coconut oil, 1.5oz of castor oil, and whatever essential oil you choose for fragrance (roughly 15g-28g
worth) is added and heated to form a homogenous solution.
-With a blender in hand, the olivel/coconut/castor oil mix is added to the vegetable glycerine/KOH mix and both of these phases are intimately mixed
and heated and then allowed to cool until a solid concentrate is formed. This concentrate needs to be mixed with 2 parts water. Apply heat to ensure
complete dilution of the concentrate into the H2O.
-Bottle and age for at least a week allowing the liquid soap to cure.
This makes a very high quality liquid castile soap that is suitable for washing your face and your privates.
Spinnbarkeit in my flask.
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CHRIS25
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Kind of you to take the trouble to tell me this. 2 gallons? wow someone needs cleaning. Anyway I am synthesizing oleic acid and will be using NaOH
as already suggested. If you see no more images up here that means I bought the darn stuff...but stubborness and desire to learn invigorates my
determination to make it.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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macckone
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Use high density polyethylene or stainless steel for a container.
The stainless steel is a better choice as it is practically impervious
to hydroxides while polyethylene will eventually be damaged.
Your mileage may with other plastics as you discovered.
For the acid stage polyethylene or glass is pretty much the only
way to go. Glass is also usable for the soap stage but will
be damaged by the hydroxide if it sits too long.
As for separating the soap from the glycerine, it depends on
how pure of a product you want. Using HCl will cause some
glycerine to partially return to the ester form so you won't have
pure oleic acid. Good luck with your damage control.
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deltaH
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CHRIS25, put your soap in a polypropylene or polyethylene tub asap, they are marked PP or PE respectively.
Yeah many plastics are not resistant to strongly caustic agents, especially anything that is designed to be biodegradible. Polyesters, for example,
have exactly the same type of bonds as in your oil, and they too can easily be saponified just like your oil ![:o](./images/smilies/shocked.gif)
Well done with stubbornly perservering, chemistry is annoying that way! Come on, we want to see you win!
**********************************************
macckone, op will be using it to prepare ferrofluid, so I doubt small amounts of reformed fatty esters would cause any problems.
CHRIS25, if you like, we could advise you how to remove this glycerine and purify your soap using a 'salting out' technique. You only
need a piece of cheese cloth and table salt to do this.
BTW, you also mentioned earier that you didn't want to use the commercial lye you had because of purity concerns as opposed to the KOH you had which
was 'lab grade'. I wouldn't worry about this too much, commercial lye is usually quite pure and significantly cheaper.
[Edited on 8-4-2014 by deltaH]
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CHRIS25
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Hallo, well second attempt using NaOH failed. It quite literally did not trace after 45 minutes of mixing, compare this with 10 minutes yesterday.
Anyway after carefully checking calculations and backtracking the only thing I could think of was the fact that I used the last 91grams of olive oil
from the bottle and this was 'dregs' so to speak. It was a slightly different colour, did not flow easily and seem divided into two products when I
noticed it; a creamy globular precipitate surrounded by a bit of 'clearish' oil, not the same flowing consistency as yesterday, I did not think that
this would matter, but I suppose that must have been the reason. There is a sale on this saturday with extra virgin oil (yes I have read about the
huge world wide corruption in the olive oil trade fooling even the big supermarkets) but nevertheless I will but a few big bottles and check the exp
date has at least two years and if it is in a dark bottle, best I can do. So postponement until saturday. Two things, yes I might as well go the
full way and do the salting out technique, another thing to learn is always good. Also macckone mentioned back titrate. Now this was naturally the
only thing I was unsure about, How to know How much HCl to use, and at 12M or dilute? Since this is not a reaction that I am used to in terms of
inorganic stoiochemetry I am afraid I need some advice on this.
So:
C60H104O6 (920g/mol) + NaOH (40g/mol) = C18H2O2Na (320)
C18H2ONa + HCl (36g/mol) = C18H34O2 (283g/mol)
Using 12g NaOH and 91g olive oil in 31mLs H2O (Using SAP value of 0.1353)
Assuming my maths is correct then NaOH concentration is here is at 7.3M and contains 0.3 moles.
And the First part of the reaction runs thus:
10.12g (0.11 moles) + 12.3g (0.3 moles) = 31.6g (0.098 moles
Now of course this is confounded by glycerine and other fatty acids and therefore in practise is undoubtedly bizarre, but this is how I have been
trying to control and get things organised. But naturally gives me no indication about how much HCl to use to get the final product.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
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Hiya CHRIS25, olive oil is a sluggish oil for saponification because of it's relatively low saponification value. May I suggest that
you warm the oil before blending to speed things up (c.a. 60C?), that should help.
Purifying soap with a salting out technique is fairly easy, though each soap is somewhat different and I can only give you a general guideline.
Dissolve your potassium soap in boiling water. I don't know exactly how much you will need. Usually, some soap won't dissolve, this is normal, so
don't just keep adding tons of water to try to get it all to dissolve. There is always some un-saponifiable matter in oil as well as low solubility
long saturated fatty acid soaps. I normally just fish this out as it tends to clump together and float on the top.
Then to salt out, wait to cool down (but shouldn't set again, if so add a little more water). Then add about a quarter of the weight of the water you
used as table salt and stir for a while. You should form masses of soap again, but this time as granules. This is because soap is only sparingly
soluble in water and as an organic compound, it separates when adding large amounts of an ionic solute. When all's done, filter through cheese cloth
and squeeze as much of the liquid out as possible by twisting the cheese cloth like a tourniquet. You should be left with a lighter lump of soap in
the cloth. Squeeze tightly!
Almost all the glycerine will now be in the water salt phase and you should have a mass of purified olive soap in your cloth. You can use this mass
for your next acidification stage.
[Edited on 8-4-2014 by deltaH]
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CHRIS25
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Absolutely you may suggest...Will do that Saturday and then sunday will upload the images. Thankyou for that salting out technique, I will do that as
well. You have been most helpful and I appreciate this. googling this yields a wealth of information I have never heard of, thankyou.
[Edited on 8-4-2014 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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CHRIS25
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Five Hours and still waiting...................
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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Etaoin Shrdlu
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Is the NaOH actually NaOH? Is it cut with something? I don't see why it would be as it's an extremely common extremely cheap commodity chemical, but
you really shouldn't be having any problems here as long as you're mixing. You do generally need to keep mixing for the soap to trace properly. Heat
helps as well. You can use it to finish things off within a day instead of letting the soap sit at room temperature for weeks.
Does the solution of NaOH/water heat up significantly when you make it up? If not there's definitely some problem with the chemical.
Can I ask the source of olive oil and NaOH? I'll try this on a small scale once I get back home and see if I wind up having similar problems, but I
don't recall anything of the sort the last time I made olive oil soap (admittedly many years ago). I don't think the problem is with the olive oil
since you got it to trace properly with KOH...
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deltaH
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Wow CHRIS25, you really know how to persevere! This doesn't seem right at all though, I agree with Etaoin Shrdlu,
something is really amiss, probably with your NaOH? If your NaOH has been exposed to the atmosphere due to poor sealing or some such, then it would
have converted to washing soda which is sodium carbonate and that would not saponify the oil.
The NaOH should have the appearance of semi-transluscent flakes or pearls (usually little beads but sometimes larger). It should not be a mass
of white completely transparent or otherwise wet looking crystals, nor should it be completely white powder, but rather semitransparent 'waxy' looking
solids.
Please confirm this and Etaoin's question about the heating when dissolving the lye in water and we should be able to help you debunk
this. He is quite right, sodium hydroxide (lye) heats up a hell of a lot when added to water, usually causing it to steam at the concentrations one
prepares for soap.
Be sure that your tub is sodium hydroxide, sometimes named 'caustic soda' on commercial tubs and not sodium carbonate, sometimes marked 'washing
soda'. I once made the mistake of accidentally taking the wrong tub of a brand that were side by side, but quickly noticed my mistake after opening
it, see my appearance description above.
[Edited on 12-4-2014 by deltaH]
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CHRIS25
National Hazard
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Hi Guys. Ok, Firstly I can assure you that the caustic soda is NaOH, Dry and kept tight. It is flowing balls! And yes, I used according to SAP
figures 40grams (just happens to be 1mole) in 94mLs distilled water (very very hot) and that was mixed with 300grams olive oil. This oil is
Primadonna from Spain, and is extra virgin. Though the chances are 90/10 that it is not extra virgin and even mixed with sunflower oil, you simply
can not tell anymore. Secondly I have used this to titrate other things and everything adds up and I have just used it to make sodium sulphate with
theoretical yields matching actual yields within a 5% error margin. I have just poured all the Soap into silicon dishes and covered for the night, it
did get thicker, but not 'gooey' thick, it did look traced after one hour of posting the image. If it is not traced I would imagine that I will wake
up to oil floating on top of a yellow mush tomorrow morning?
I still do not know how to measure out the correct amount of HCl, i presume to put a fairly concentrated amount in until I see a precipitate, since
oleic acid is insoluble in water, I suppose I had better use a fairly dilute soln HCl maybe just 1M?
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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deltaH
Dangerous source of unreferenced speculation
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Location: South Africa
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I'm truly amazed! Normally when making olive oil soaps, one always blends the olive oil with other fats that contain more medium chain
triglycerides... now I know why... the long chain fatty acids simply saponify too slowly on their own under mild conditions it would seem.
I will ask you a funny question now: do you have a pool shop near you or a decent pool section at a hardware store or supermarket? If so, have a look
at the algaecide products, specifically one for black algae (usually labelled as such). Then have a look at the active ingredients, see if you can
find one that says it's based on something called dimethyldidecylammonium chloride or a similar name to this without other ingredients beside water. I
will explain to you further how you could use this to possibly speed up your reaction greatly, employing it as a phase transfer catalyst, but
only if you can find this OTC in Ireland as we can in South Africa.
As for the concentration of the acid you would use, experiment, 1M should be a good start I would guess.
[Edited on 12-4-2014 by deltaH]
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