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View Full Version : OT -- Shaking Redi-Whip cools it. Why?



Orrin
10-29-2007, 10:21 AM
Last night we served pumpkin pie to a guest and as she topped it off with Redi-Whip she asked, "Did you know that shaking this can of Redi-Whip causes it to cool off?"

I pretended to know, so the topic was dropped. I can guess, but there's probably someone in the forum who knows for sure.

Here's my theory: During the time the container sits un-agitated, volatiles condense and go into solution. When the can is shaken, they are driven out of solution. In the process they pick up their heat of vaporization from the non-volatile portion of the contents, thus lowering the temperature.

Is this far off the mark? Any other explanations?

Thank you.

Orrin

lynnl
10-29-2007, 10:37 AM
As an ex-meteorologist, I would say you've nailed it right on the button.
That's certainly the process that takes place in the atmosphere, and I can see no reason it would be different in the can of Redi-whip.

agrip
10-29-2007, 10:48 AM
It is also possible because of viscosity and k of internal hodgepodge, that the core mass was cooler than the surface of the can. And on agitation the core temperature became apparent.

Hth Ag

Evan
10-29-2007, 11:32 AM
It is also possible because of viscosity and k of internal hodgepodge, that the core mass was cooler than the surface of the can. And on agitation the core temperature became apparent.

Yep. There aren't a lot of "volatiles" in Redi Whip. Even if there were that wouldn't happen. It's simply a viscous solution so convection doesn't operate well. Agitation does.

A.K. Boomer
10-29-2007, 12:26 PM
My first thought was also along the same line as Agrips with the additional "why was she shaking the can and did she actually use some" cuz if she used some that would really make a big diff.:)

darryl
10-29-2007, 12:48 PM
The refridgerator of the future- still a motor, but instead of a pump there's a balanced array of - redi whip cans. :)

Yeah, shaking it just brings the contents into more contact with the sides of the can, so you get some heat transfer. Initially the can and its contents are at the same temperature, but when you pick up the can your hand warms the thin metal very quickly. Only when you bring the liquid contents of the can up the sides do you feel the temperature of the contents. It will be cooler than your hand, so you feel it as a temperature decrease.

Forrest Addy
10-29-2007, 01:01 PM
Nah! The can is full of notsigolhp the (inverse of phligiston) to induce the spirit of the whipped cream to fluff up and flow from the nozzle. It's the same effect as the moon has on the tide. It's tha same effect that makes the moon slowly drift away which is why we're getting global warming, and why ice cools hot drinks. Refrigeration is different. When you pound on a gas you get the RAP effect - continual monotenous noise makes things cooler.

If you can't understand science these days, you're helpless.

Guido
10-29-2007, 01:16 PM
I've no arguement with any of the above, but-----------

I've explained to the wife how a thermos bottle will keep hot liquids, hot and how the same bottle will keep cool liquids, cool. She said she already knew that, but her question remains: 'Yowbutt, how do it know'.

G

Jim Hubbell
10-29-2007, 04:44 PM
Looking at from another side, it actually warms the contents because of the energy gained from shaking.

Maybe combined with previous theorys we have a standoff.

Fasttrack
10-29-2007, 06:03 PM
The amount of kinetic energy you apply by shaking it is very very very tiny compared with the actual temperature of the system.

If you put a thermometer in a pan and then start stirring really fast the temperature doesn't suddeny increase because the kinetic energy added to the system is small compared with the vibrational and rotational energy of the molecules.

topct
10-29-2007, 06:59 PM
Redi-Whip is charged with nitrous oxide. When you shake the can the compressed gas, being cold, mixes with the mixture in the can. Chilling it.

Redi-Whip cans do not have a tube that reaches to the bottom of the can. You have to hold the can with the nozzle down to get it to make whipped cream.

If you hold the can upright without shaking it and pushing the nozzle, all you get is the gas. This is why you can't spray Redi-Whip on the ceiling.

Benesesso
10-29-2007, 07:07 PM
:) :) >"If you hold the can upright without shaking it and pushing the nozzle, all you get is the gas. This is why you can't spray Redi-Whip on the ceiling."<

Sure you can. Hold the can upright over your head, yank it down fast as you push the nozzle. When there's a will there's a whey---.

speedsport
10-29-2007, 07:16 PM
If 2 or more ingredients are mixed together to form a solution and then seperate if left still were they ever a solution?, if I remember my high school science class the answer is no.

topct
10-29-2007, 07:23 PM
:) :) >"If you hold the can upright without shaking it and pushing the nozzle, all you get is the gas. This is why you can't spray Redi-Whip on the ceiling."<

Sure you can. Hold the can upright over your head, yank it down fast as you push the nozzle. When there's a will there's a whey---.

I will try that.

Benesesso
10-29-2007, 07:38 PM
Please post a photo!

Fasttrack
10-29-2007, 07:41 PM
If 2 or more ingredients are mixed together to form a solution and then seperate if left still were they ever a solution?, if I remember my high school science class the answer is no.



Your bang on - if they seperate they were not a true solution. They were in suspension or possibly they could have been in a colloid although colloids don't readily seperate, they need something besides just gravity to make them seperate. (Smoke would be an example of a colloid)

Evan
10-29-2007, 08:13 PM
Redi-Whip is charged with nitrous oxide. When you shake the can the compressed gas, being cold, mixes with the mixture in the can. Chilling it.
Assuming the can hasn't been used why would the compressed gas be at any other temperature than the rest of the contents? Further, the heat capacity of nitrous oxide is far less than the cream emulsion (not solution). The cream will warm the gas if it has chilled from being partially decompressed. The effect on the emulsion's temperature will be negligible.

Your Old Dog
10-29-2007, 08:51 PM
It really doesn't matter.

What really matters is that you had the presence of mind to answer as you did :D You are wise beyond your years!


I pretended to know, so the topic was dropped.

rkepler
10-29-2007, 09:23 PM
Skipping past the anecdotal I went right for the experimental.

Taking a new can of Kroger's Heavy Whipped Cream I duct taped a type-K thermocouple to the side, about an inch up. Over that was duct taped a paper napkin folded over to about 8 layers, this for casual insulation. After letting the can, thermocouple and my Fluke meter sit in the fridge for 30 minutes (causing the question "what the hell is this?" from SWMBO) I turned on the meter and waited the for temperature to stabilize. Fridge was working so I got 39.1 degF. Waited a second and it went to 39.2 Stayed there so I grabbed the can and shook it a bit, same as I would if I was ready to spritz some pumpkin pie. 39.2, 39.3 OK, experiment done.

The experiment setup:

http://www.kepler-eng.com/images/experimental_setup.jpg

Now I have to make some pie.

speedy
10-29-2007, 09:37 PM
Down this way we use real cream and mix it in the bowl. No temperature change there either, just a squabble over who gets to lick the spoon, fork or whisk :D One pint of whole cream equals 1 pint. How much do you get in an aerosol can?? Bugger all??:p and how much preservative etc if any??

Ian B
10-30-2007, 04:33 AM
Well, here's my guess at what happens;

When left still, the 'cream' (or whatever they put in there) degasses and settles to the bottom. Propellant gas is at the top, separate.

Invert the can without shaking it and gas-free cream comes out. The gas remaining in the can expands and therefore cools, but this leaves you with warm (expelled) cream and a cold can.

Shake the can first and mix the propellant gas in with the cream. On spraying the cream out of the can, the bubbles of gas now mixed in with the cream expand and thereby cool the cream.

Either way, the total amount of heat energy in the system hasn't changed, but shaking it first ensures that more of the original heat remains in the can.

Ian

Barlow L
10-30-2007, 08:00 AM
Some of you may remember back when you bought a whip cream dispenser, whip cream, and a box of "whip it's". The "whip it's" were Nos, in cylinders the size of a Co2 cylinder for pellet guns. The Nos pressurized the dispenser and chilled the whip cream.

I haven't seen them in stores for years now. Guess they figured out the hippies were inhaling for a laugh.

Lee