DarwinStrings wrote:liam_fnq wrote:Ii'm in the same boat. The hardware meths is 95% meths, 5% crap so I'm off the the local chemical retailers to get high quality meths. Try local mobs that supply bulk cleaning chemicals
Now I am not 100% sure about what exactly the all of the other 5% is in hardware Metho is but on the bottles it says "95% v/v Ethanol" I assume that part of what goes to make up the other 5% is Methanol and it may well be 5% Methanol. I assume everyone knows that the Methanol is added so that we can't have cheap fruit punch at parties or maybe after having been to a few parties where the party throwers had access to surgical Ethanol it is the governments way of saving us from the sort of hangovers that that sort of party punch can dish out, hmmmm am I being over optimistic about our governments concern for our well being?
Jim
Jim,
You are correct that Methanol or some other denaturing agent is added to bottled metho to prevent it from being consumed as cheap booze. However the denaturing additive should NOT be included at all when considering the active ingredient on the label. From my understanding to assume that the denaturing additive must make up the 'alleged' missing 5% of "95%v/v Ethanol" to make 100% of the contents in the bottle is wrong simply because "95%v/v Ethanol" is presented as advice of purity for the ethanol 'azetrope' that remains after distillation and 'before' anything is added to it.
So even if you were to somehow remove the denaturing additive from the formulation entirely, the bottle could still only ever contain "95%v/v Ethanol" because that is purest form of ethanol that 'simple' distillation as employed by manufacturers of metho is able to achieve. So the reality is that its not actually ethanol, its an ethanol azeotrope. In other words it is a combination of liquids that cannot be broken by simple distillation and what remains is 95% pure ethanol and this is why it only cost a couple of bucks a bottle to buy and they can still make money.
http://www.google.com.au/url?sa=t&sourc ... WJl0NAl-9Q
Now, if we want to remove that 5% from the azeotope that is polluting our Ethanol so we can produce an absolute, then we need to go back to my drag racing analogy where big bucks and effort are required for little gain, and that is exactly what happens when you move into azeotropic distillation. This requires the addition of more substances that will target the impurities to form a second, 'low boil' azetrope which upon distillation will effectively break the first azetrope and scavenge the impurities from the ethanol to leave behind an absolute.
But now we have that high maintenance issue I mentioned earlier because our hard won absolute is a very unstable substance......we all get a bit like that if left in isolation for too long, so as soon as you take the lid of your bottle of pure ethanol, it will degrade very rapidly to 96%, because that is where it want to be, and it wants to be there so much that its molecules will actively suck water right from the air until the the solution is 96% ethanol and 4% water and then it will settle down into a normal hygroscopic pattern and degrade more gradually as more water is drawn into the solution to make it more stable. Google has told me (with no great authority) that if left long enough with adequate moisture in the air, this process will eventually stop at a 1:1 ratio....
So what does this mean for our hardware grade metho?? Is the "95%v/v Ethanol" referred to on the label 'really' free of water??....Very unlikely, the fact that the ethanol is in an azeotropic solution does not mean that the attraction is lost between ethanol and water. So yes, at the time of distillation 95%v/v Ethanol was probably accurate, but unless extraordinary measures where taken with air driers and whatnot employed during bulk storage, decanting and bottling, then there is little chance that it would be still accurate by the time you first take the lid off the bottle, and the truth is that what's most likely to be in the bottle when you get it home...and this also goes for products such as Everclear labeled as 200% proof, is the original ethanol represented by % of purity at the time of distillation + any impurity that formed the remainder of the azeotropic solution + at least 4% water unless you where paying an extraordinary amount of money for lab grade + any additives to cause denaturing....and the last two of those are never mentioned on a bottle of metho and really when it comes down to it, what could you really expect for a couple of bucks.
And here's one out of the woods....if you have a graduated beaker containing 'exactly' 1000ml of absolute ethanol and you expose it to moist air for a few minutes so it takes up 4% water, you could easily assume that the beaker would now hold 1040ml....wrong again, it is likely to be closer to 1030ml and no, 10ml of ethanol did not evaporate...apparently this has something to do with the oxygen atoms in the ethanol being so attracted to the hydrogen atoms in water that it makes the solution more dense...so yes, the weight of the 40mls of water is now there, but the solution has not increase in volume as one would expect.
If you think about that for a moment, the strength of that attraction, of oxygen to hydrogen being so great that it changes the 'density' of the solution, its really a form of compression of the solution itself...Yeah I know, that is probably not a very scientific view because we all know that liquid's cannot be compressed. But what I am saying here is that to my unscientific mind, we have a process at play that is much more than simply hygroscopic in its nature where water is gradually drawn to a receptor.....this is different, its a powerful reaction of a highly unstable substance that actively 'pulls' water from the air with such veracity that it increases in weight but not so much by volume...so don't wonder why you wake with such a dry mouth after a night out with the lads.....ethanol/alcohol is very much a sponge and it is literally sucking the water right out of you....best keep a lid on it when doing FP I recon.
Cheers
Kim
