How does water still freeze even with glycerol or salt added to it?

[Elite Engineer]

I know that glycerol, anti-freeze, and salt can be added to water to depress it's freezing point. These substances essentially interfere with hydrogen bonds between water molecules, so there isn't any lattice crystal structure being formed.

 

But when the temperature gets cold enough, the water does eventually freeze/ form lattice structures. My question though, is HOW? There's literally a molecule blocking adjacent water molecules from interacting, so how does a lattice structure still form?

 

~EE

[swansont]

There's literally a molecule blocking adjacent water molecules from interacting, so how does a lattice structure still form?

 

Is there?

[Elite Engineer]

Is there?

Well in the case of charged ions, no. But I ma referring to larger molecules, like glycerol, and ethylene glycol that would wedge their way in between water-water interactions.

[fiveworlds]

lattice crystal structure being formed

 

 

 

A solid is when atoms move too close together. When atoms have more kinetic energy (heat) constructive interference occurs allowing particles to move farther away. Therefore pretty much everything should become a solid when it is cold enough.

 

But I ma referring to larger molecules, like glycerol, and ethylene glycol that would wedge their way in between water-water interactions.​

 

 

The colder the glycerol etc is the interference it generates to stop the water-water interactions.

[John Cuthber]

The defining point of a liquid is that all the molecules are moving. So all it has to do is wait until the salt or glycerine moves out of the way.

[Elite Engineer]

all it has to do is wait until the salt or glycerine moves out of the way.

But then it wouldn't matter if it were 0 C or -50 C, the water would freeze regardless of temperature. I'm assuming that water molecules create a stronger H-bond with each other in an ice lattice than with the OH groups attached to the 3 carbon chain..because isn't the glycerol slightly more non-polar than water? Much like how isopropyl alcohol is more non-polar than methanol because of the 3 carbon chain.

 

My thought is, the colder it gets, the higher the chances the water molecules form a stronger hydrogen bond, meanwhile the glycerol just kind of flows around them...similar to a size exclusion chromatography column.

Edited January 9, 2017 by Elite Engineer

[John Cuthber]

The freezing point is the temperature where they stick together more often than they fall apart.

Having an impurity present makes the probability of sticking together smaller.

It doesn't matter much what the impurity is.

https://en.wikipedia.org/wiki/Freezing-point_depression

[BabcockHall]

It has been many years since I studied freezing of glycerol solutions. IIRC at about 67% glycerol, one never actually sees freezing, but instead one gets a glass. There is some good literature out there because of electron microscopy, low temperature EPR studies (EPR spectroscopists prefer glasses), and crocrystallography. It took me a while to tap into it, though.

Edited January 19, 2017 by BabcockHall