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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: sugaJ on July 02, 2009, 06:47:16 AM

Title: Why does antifreeze have low viscosity?
Post by: sugaJ on July 02, 2009, 06:47:16 AM

I'm stumped on this question. Ethylene glycol, or antifreeze has O-H groups and it seems like a fairly large molecule. Both of these usually increase viscosity so why does ethylene glycol have such a low viscosity?

Any help would be much appreciated.

Cheers

Title: Re: Why does antifreeze have low viscosity?
Post by: lancenti on July 03, 2009, 04:16:42 AM

You're going to need much more than polar interaction to make something viscuous.

Ethylene Glycol is just about as big as Ethanol, or maybe Propanol, so there isn't much ID-ID interaction going on. Since it has two -OH groups now, it just makes it something like, say, water (I'm obviously oversimplifying here).

To make it viscuous, you'll want a longer hydrocarbon chain - say maybe octane.