Quince - 11-10-2005 at 22:02
If mixing two liquids with different refractive indices, would the resulting index be between that of the two separate (and more specifically, a
linear combination w.r.t. their specific weights)?
I need a relatively non-toxic clear liquid with index of refraction very close to that of glass, so I was thinking benzyl benzoate dissolved in
isopropanol, as the former's index is a bit higher than glass, whereas the latter's is a bit lower.
Or are things not that simple?
denatured - 11-10-2005 at 22:24
I think you are right ... the refractive index will be a balanced reading between both benzyl benzoate & isopropanol. as the refractive index
changes readily when slight changes in the liquid's consistency happen.
unionised - 12-10-2005 at 09:27
It will be close. If the 2 liquids interact then the answer won't be correct but with the 2 you have chosen it shouldn't be a problem.
In particular, steer clear of combinations that give azeotropes or large delta V of mixing. Then again, alcohol and water form an azeotrope and have a
significant delta V but you can still use n to measure the concentration over a reasonable range.
vulture - 12-10-2005 at 11:18
Won't there be some hydrogen bond interaction between the carbonyl function of benzylbenzoate and the hydroxylgroup of isopropylalcohol?
[Edited on 12-10-2005 by vulture]
Quince - 12-10-2005 at 19:18
I got the idea since benzyl benzoate has been used as a mixture with benzyl alcohol to match high refractive index polymers. However, with such a
mixture I can't get glass refraction, so I thought to use a different alcohol.
BromicAcid - 12-10-2005 at 19:35
What type of glass are you trying to match the refractive index of? Some time ago I needed to do a reaction and put a apparatus on the end to prevent
suckback that involved a glass tube extending into a basin that I filled with mineral oil. When I added the mineral oil I had to remove it again
immediately, why? Because the glass tube had completely disappeared, so much so I could not discern it no matter how much I looked into the liquid, I
thought it had broken off, but when the oil was removed it was of course still there. What I'm saying is that mineral oil is somewhat close to
the refractive index of glass and probably matches some glasses avalible commerically.
Quince - 12-10-2005 at 19:51
The glass is probably Pyrex; I haven't gotten it from the glassmaker yet. Mineral oil is very close, but how do I adjust up and down (looks like
down)? A Google search shows it's not miscible with ethanol, but what about other common alcohols?
[Edited on 13-10-2005 by Quince]
The_Davster - 12-10-2005 at 20:10
I have a mixture of carbon tetrachloride and benzene that has the same refractive index as glass, its in a book I have somewhere, if you are
interested I can dig it out for you tomorrow.
Reagents needed are definatly harder to get though...
Quince - 12-10-2005 at 22:32
It's for a university project, so getting reagents is not an issue. The problem is benzene is carcinogenic, and slushing around a couple of
gallons of the stuff is out of the question (this is not a chemistry project, and we don't have a wet lab).
Also, I need to be able to dissolve a good deal of dye (such that at least 90% of light going through 15 cm of the stuff is absorbed). Most dyes
I've tried won't dissolve. Permament markers do pigment the mineral oil, but not very well.
[Edited on 13-10-2005 by Quince]