Critical content of Oil in Water

Amalgam is the wrong term. Emulsion is perhaps more appropiate. Water and oil are inmiscible and will separate in two layers; water will sink to the bottom.

Dear Coffeebean

You're right about emulsion. But will it hppen even if say 0.01% water is mixed with 99.99% pure oil by vigourously shaking them for hours together?

Well, my guess is that so long as there is free water present and given sufficient settling time it will eventually separate out even if the water layers is a few molecules thick. We are assuming a pure oil-water mixture, no surface active agents present.

Emulsifiers & Deimulsifiers are commercial concoctions.Google-and you see all!

So also my favourite --ELECTRO COAGULATION to de-emulsify.

mm

The answer is it all depends on the oil used some oils will separate out very quickly others will hold the water at a molecular level. Take the instance of when a head gasket goes on your cars engine and unaware you drive around for some time then when it becomes obvious to you, you decide to take a look there you find a nasty emulsified mess under the oil filler cap. So given the right conditions it can be that oil and water will mix.

It depends on the oil and whatever is dissolved in the water.

Some thoughts:

Diesel (or gas-oil) will support a small amount of water, its presence being a nuisance for the purposes of combustion in an engine and its dissolved and suspended substances a nuisance that confounds the worthy ambition of keeping the injectors clean.

Benzene/ethanol/water forms a good mixture. Benzene is introduced into ethanol/water in order to achieve a greater ethanol purity than the eutectic point in the phase diagram would indicate.

What about margarines? Shaking a water/oil mix will produce one result. Passing the mix through an emulsifier will produce another.

I spotted Margarines these are an entirely different case to those of a true emulsion.

Surely margarine is made by combining oil with hydrogen at hi-pressure. Not exactly a normal emulsion?

THe issue is not what you have been lead to believe.

Throws out all my Chemistry training:

http://www.newscientist.com/article.ns?id=dn3408

milo

Some of the water will separate out and settled at the bottom. How much volume of water that settling down at the bottom is depend on the water separability of the oil. Synthetic oil have better water separability than mineral oil

The oil and water will separate, given a number of factors.

Specific gravity of oil, temperature, presence of soaps (promoting chemical emulsification), mechanical mixing such as from a submersible pump or pressure washer as in a car wash(mechanical emusification), and time. Bench testing is one of the best ways to see what you are going to get. Take a sample and mix it up, then observe the time it takes to separate. With clean water and oil in a flask, you will see the still mixed layer in the middle as "foggy" Decant the bottom layer of water and test for TOG (Total oil and grease) content.

http://www.greenturtletech.com/

We're thinking that someone who is asking "Will water and oil separate?" as a "What if ?" question probably doesn't have the means to do a Total Oil and Grease analysis. If they had the oil and water that they were asking about they could have done the test themselves and wouldn't have needed to ask. Linguistic barriers prevent us from truly understanding the question.

milo

Oil in a bearing of a running motor may have become contaminated with water ingress resulting in the bearing failure. The failure led to fire which was extinguished with water. Subsequent sample analysis showed 20% water in the oil sample taken out from the bearing of an identical bearing on a similar motor located near the damaged bearing of motor-1. The point is whether gradual contamination of oil with seeping water could have led to 20% water in oil (sample collected 3 days after the motor was stopped contained separate oil & water) or it was water from fire extinguisher that was found later. One school of thought is had the water seeped in gradually in the running motor-2, it would have remained stable as a emulsion - but since it was clearly separate water & oil mixture, the source of water was fire extinguisher. In case the source of water is fire extinguisher, the explanation for motor-1 bearing failure lies exclusively somewhere else. This was the triggering point of placing the question.