Should Toluene be clear or cloudy white?

n0_3sc

I have very little background in chemistry.
A clear sample of toluene was poured into a non sealed bottle and after several hours it turned cloudy white.
Is this normal?
Why does this happen?
It is still a clean solution of toluene right?

Borek

It shouldn't, there is some contamination. Was the bottle dry?

Borek
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lightarrow

Or the bottle was not dry (or contained something that mixed with toluene) or the liquid has absorbed humidity from air.

n0_3sc

Hey,

The bottle was rinsed out with distilled water but not thoroughly dried. It sits in a near dust-free environment where temperature and humidity are controlled. The bottle had no previous chemical substance in it. Not for >3 years that I know off.

lightarrow

So it could be the little amount of water still present in the bottle after rinsing out.

n0_3sc

really?? distilled water can be a contaminant?

Mike H

Yes, water can be a contaminant. Given that toluene's solubility in water is quite minimal, even a tiny bit of water can serve as a contaminant. Many organic solvents - including toluene - are typically sold as "dry" solvents (water-free or nearly so), since even a small amount can screw up someone's work.

Asphodel

Let's see - is water a chemical?

GCT

I'm not quite certain if water and toluene would mix to form a suspension you might want to observe a mixture without stirring it ; should find two immiscible phases. From my experience a small amount of water in certain organic substances forms a cloudy suspension with stirring ; at times at 2% however it should be higher for toluene. Surfactants can cause reverse miscelle formation with water and toluene also.

n0_3sc

I think I found the cause of the problem (along with water). The toluene was sandwiched between two transparent pieces of plastic. Apparently you can't place these chemicals on plastic due to some effect? The plastic turned all opaque and "cloudy white".

Borek

Toluene is a pretty good solvent, it will penetrate many plastics and it will dissolve them to some extent.

Borek
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