So, there’s a Facebook post that spraying your already frozen up windshield and windows with a 2/3 solution of vinegar to 1/3 water will magically melt the ice from your car.
Snopes is rather inconclusive and states that the original story was to spray your windshield with this formula before the freezing rain comes, and then magically just wipe it off.
I’m skeptical.
Is there any reason, from a chemistry perspective, that this should work?
Vinegar may have a lower freezing point than water in which case that’ll melt the ice. OTOH, just putting room temperature water on ice will melt it as well.
ETA, some quick googling says that vinegar freezes at 28 degrees. If you mix it with water it’s going to be somewhere between 28 and 32. There might be some chemistry involved, but it might just be that you’re pouring a warm liquid on ice and melting it.
Sorry, the application described is by spray bottle.
you can’t just interpolate between the two materials’ freezing points. look at the antifreeze solutions used in cars (and elsewhere.) They’re a mixture of water and ethylene glycol. Water freezes at 0°C, ethylene glycol freezes at -12°C. a 60%/40% mix of ethylene glycol/water will freeze at -45°C.
[runs to wiki]
Strange, I never would have guessed that.
I’ve always told people that you can’t just keep topping off your radiator with water, even in summer, because the antifreeze pushes the boiling temp UP. Now I know that you can’t just keep topping off with antifreeze in winter since you need the water to push the freezing temp lower than it would be with just straight ethylene glycol (we have plenty of sub 10 degree F days here in Wisconsin).
Or you could just move south… What?
Wouldn’t vinegar, even at that solution, tend to do bad things to your paint job, windshield wipers, and/or other stuff it’s allowed to stay on for a while. I guess you could rinse it off thoroughly, but then you’d have probably been better off just doing that in the first place. (Though I have no experience deicing a car, so little that I don’t even know if I spelled it right!)
I can’t imagine what it would hurt. If you’re worried, maybe keep it off the paint/clearcoat, but it’s just going to trickle down the firewall.
like salt, the acetic acid in vinegar lowers the melting point of ice. Unlike salt, it is a volatile compound an therefore will evaporate after it has done its job.
To clarify, this is known as the molal freezing point depression and it also helps that both the salt (sodium or calcium chloride used in winter on roads) or vinegar produce ionic solutions which, in effect, doubles the molal concentration.
Vinegar (which BTW is a 5-6% solution of acetic acid in water) is much handier to use on windshields.
The phase diagram for acetic acid - water mixtures (as already mentioned, vinegar is about 5% acetic acid in water) can be seen at the link below. The important sections are on the far left side. Zone A = all liquid; B = slush; D = solid (“vinegary” ice).
If the temp is much below freezing, the vinegar solution isn’t going to help much because it will be in zone D - all solid.
If it’s just below freezing, you may get into zone B and have enough liquid present to make the wipers useful for removing it.
On the whole, I think running the defroster for a few minutes would be just as handy as the vinegar thing.
http://chemistry.stackexchange.com/questions/2506/acetic-acid-freezing-distilation
also important to not put liquids at a drastically higher temperature (of the windshield) on the windshield because you might crack it. a bottle of windshield washer fluid that is in the cold car could work sprayed on the outside.
to be technically correct (the best kind of correct!) boil-over protection is largely due to the cooling system being pressurized while the engine is warmed up. looking at the Ford Fusion I have here, the cooling system is pressurized to 21 psig at normal operating temperature which for pure water would raise the boiling point to 126°C (260°F.) The glycol mix would raise it a bit more.
When I lived in England I used an empty dish washing container with about 10% Methylated spirits in water, squirt on the screen and the ice melts straight away. Worked a treat and never damaged the paint work. Leave small traces of dishwasher liquid for a sudsy affect.
I suspect that it’s at least partly due to the difference in polarity between the two molecules. Mixing them up disrupts the crystal formation for both of them. (Perhaps that happens even without difference in polarity.)
Well, salt and vinegar are different. Salt entirely ionizes, or nearly so. Acetic acid is a weak acid, so only a little bit of it ionizes.
To be accurate, you would have to take into account the fact that both of these solutions are well above the concentrations established for the Debye-Huckel Theory and the corresponding Limiting Law. Therefore the salt (sodium chloride) is not fully ionized either as it’s activity coefficient would be approximated by the square root of the total ionic strength at very low total solution concentrations (less than 0.01 M as I recall) and even lower at higher concentrations.