peroxide question

[Bjl84]

i have a couple of bottles of peroxide 3% one unopened and one half full that i left out in my shed the other day, and apon finding them this morning noticed that the half full bottle is the consistancy of a slushy and the other unopened is i am assuming the same, now my question is does this happening render it useless to the refining process (ap) or does the the cold not effect it's "chemical potency", Any insight would be most helpful as i am not sure weather i should call it a loss and go buy new or not

 

[butcher]

Well my guess is no, it should be OK, I would worry more about heat on a summer day more than the cold weather, the hydrogen peroxide is water with an extra oxygen, hot solutions would loose gas easier than a cold solution, so a hot summer day would drive off more oxygen gas from your bottle of peroxide, that storing the hydrogen peroxide in your refrigerator would, cold solution hold gas easier.

I assume the slush you see is just water beginning to freeze. H2O2 in the unfrozen part of the liquid I assume would just be more concentrated, when the Ice thaws it would most likely mix back with the frozen water in the bottle.
I would say your hydrogen peroxide is just fine, if it was mine and I wanted to check it I would probably wash my mouth out with it, or pour some in my ear, or on a cut, and see if it still had its oxidizing power.

Update:

So on a summer day you should not loose H2O2.
water can be evaporated before the H2O2 decomposes.
From this we can concentrate 3% H2O2 to a higher concentration by heating the solution below the boiling point of water and evaporating water off of the solution.

 

[Bjl84]

thank you for the insight butcher much appreciated

 

[goldsilverpro]

I doubt if there would be any separation and concentration of the H2O2. I believe that H2O and H2O2 are completely miscible and there is also chemical bonding. The freezing point would be depressed a bit below 0C, maybe a few degrees with 3%, more with stronger solutions. I would think that, because this is true, that they are freezing together.

 

[butcher]

I have never tried so all I can go by is what I have studied, sometimes I do not remember things right, or can be wrong about what I think I Know.

Besides the chart above showing the freezing point of H2O2 at various concentrations, there is more evidence that water freezes at a slightly higher temperature than H2O2, although not the best method of concentration, it does seem possible to freeze water out first, to obtain a slightly higher concentration of H2O2.

I think the key is found in wiki, stating Hydrogen peroxide and water form a eutectic mixture.


Physical properties of hydrogen peroxide solutions
In aqueous solutions hydrogen peroxide differs from the pure material. This demonstrates the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression. Pure water melts and freezes at approximately 273 K, and pure hydrogen peroxide just 0.4 K below that, but a 50% (by volume) solution melts and freezes at 221 K. The boiling point of the same mixture is less than the average (398 K) of the boiling points of pure water (373 K) and hydrogen peroxide (423 K) at 387 K.[10
http://en.wikipedia.org/wiki/Hydrogen_peroxide
http://www.sciencemadness.org/talk/files.php?pid=282573&aid=23323
http://en.wikipedia.org/wiki/Eutectic

http://books.google.com/books?id=YyoUNYgBYJoC&pg=SA1-PA96&lpg=SA1-PA96&dq=concentrating+H2O2+by+freezing&source=bl&ots=OTHaED_BBp&sig=EnljtrIs6oPyKYFiKBdNJKvzKqc&hl=en&sa=X&ei=X2iaUoyoM4b6oASXq4HgCg&ved=0CGoQ6AEwDDgU#v=onepage&q=concentrating%20H2O2%20by%20freezing&f=false

Correction:had written water should have said H2O2

 

[goldsilverpro]

Sorry, Richard, but I can't see that happening. I read the same stuff you read. I see it as being a single unit. They freeze together.

 

[butcher]

I will continue to look into this.

I do not think the water and peroxide separate completely in the ice, but from what I can gather so far they do somewhat separate by their freezing points and H2O2-H2O can be separated from the frozen H2O by freezing thus concentrating the hydrogen peroxide portion.

Chris you are making me work on this one, that is great I will learn more about it.

 

[goldsilverpro]

The freezing point of pure H2O2 is only about one degree F below that of H2O.

Check the freezing point chart on this link, page 15. To me, if there were separation, this chart would be in error. It's one unit, not two.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDQQFjAB&url=http%3A%2F%2Fwebserver.dmt.upm.es%2F~isidoro%2Fbk3%2Fc07sol%2FSolution%2520properties.pdf&ei=LbGaUpbYF47noAS6zYGICg&usg=AFQjCNFRNkb5MGNHXtqsIdiqWPd_p9Aavw&bvm=bv.57155469,d.cGU

I don't think either one of us really truly know the answer. Maybe a real chemist could join in.

 

[butcher]

From what I can gather the freezing point changes depending on hydrogen peroxide concentration.
I am having a hard time trying to say what I am trying to.
3% H2O2 would be just a bit colder than the freezing point of the pure water.
With higher concentrations like 20% H2O2 having a greater separation of its freezing point from the freezing point of pure water.
I do not think the frozen water, in a solution of H2O2, will be like freezing water out of salt water like the ice in the glaciers, where the water could freeze with out being salty, I imaging both products would have both components, but that the ice could hold less H2O2 and be closer to pure water,with the un-frozen portion the remaining at a higher concentration of H2O2-H2O, leaving a higher concentration of peroxide.

Alcohol as we know can be distilled in a heated still to give a higher alcohol content in the condensed solution, but also can be somewhat be separated from water, and concentrated by using its Eutetic mixture and (freeze distill) the whiskey separating water as ice.
This ice would contain some alcohol taste, but would be closer to pure water, leaving the other un-frozen portion of the solution with a higher alcohol content.

I have read several places where they can concentrate H2O2 water solutions up to 30% by the freezing method, I think because of the temperature below zero degrees centigrade needed it is probably hard to do this further, and then they can distill evaporate water off the hydrogen peroxide to concentrate it up to 90% or even crystallize it.

Chris you are right, I do not understand this well enough, it is hard to wrap my mind around the idea, of separating hydrogen peroxide-water from just water, but I sure would like to learn more about it, I think it would help me understand more of how some things in solution are not always how I think of them.
Oxygen and water seem to be a very strange animals.

 

[Richard NL]

The first part of this you-tube for a visual idea:
https://www.youtube.com/watch?v=sMZS_arPUhM&list=PL11BF37F092BB1C16&index=18

One way of making industrial hydrogen peroxide.
http://tinyurl.com/lumr7j8

A very good read:
An Introduction to the preparation and properties of hydrogen peroxide.
http://tinyurl.com/oqe4pmj
Same book:
http://tinyurl.com/m2n3ntw
(If a moderator wishes to remove a link feel free to do so,possible copyright infringement)

Best regards,
Richard.

 

[Harold_V]

(If a moderator wishes to remove a link feel free to do so,possible copyright infringement)

Best regards,
Richard.

It would be my opinion that so long as you provide a link, not quoted text, there is no copyright infringement.

Harold

 

[Geo]

According to the book, hydrogen peroxide and water do not form azeotropic mixtures and can be completely separated by distillation. With the boiling point of hydrogen peroxide being 150°C and the boiling point of water being 100°C, you should be able to evaporate water from the solution concentrating the hydrogen peroxide. Not a good idea to heat but a desiccator would work okay I would think.