Weight and Heat

depends on how accurate and the precision your weight has to be, and what flares off at higher temperature.

Sadly, this is all too common of an answer! My ex used to say the same thing and she is edjumakated with several college degrees!

(That I paid for)

Besides being an amazingly clever woman, my colleague has a degree in organic chemistry and a PHD in Polymers.... and so much knowledge canned in a single brain makes me doubt on how much I know!

If that's the case why can't she calculate the difference in weight that she claims is present and adjust the amount to be added accordingly?

Her reasoning is flawed anyway because if the weight does in fact change, and that seems to be in dispute, whatever percentage you add will change by the exact same proportion as the original lot did once the new lot has been brought back up to the same temperature as the original lot after they've mixed and integrated.

If she's not convinced by that then tell her to separately heat the percentage you want to add up to the same temp as the original lot and then add it to the original lot, so whether it's lost or gained weight it will be in the exact same proportions as the original lot.

Weight and mass are not the same. Weight is do to gravitational pull. Mass the amount of matter. Actual if you heat matter it weights more. But the difference is very little.

Don't lab mixtures require that they be done at a certain temperature. So that these discrepancies don't occur.

I agree with you about weight and mass, BUT weighting a certain mass in the same geographical location (same gravitational pull) ratio remains 1:1.

According to you, why does hot matter weight more?

E=MC²

Yes, but you try to measure the difference in mass between a hot and cold body, or between reactants and products of a chemical reaction

Ozzb: Are you referring to E=mc² as applied to the thermal energy added to a system would increase the mass of the system. Technically, yes, it does, but practically (and this is supposed to be common sense, engineering) it does not. Sometimes people argue over silly things that have no bearing upon the final outcome.

That is just juman nature. R&D Doc needs to tell his high-spirited assistant to take a few laps around the lab building, and come back un-flustered.

Volume varies with temperature.

Put a beaker filled with room temperature water on your analytical balance.

Weigh it.

Heat the beaker to 60C.

Weigh it again.

I will not admit that I have done the beaker test you mentioned, and that the result is as you anticipated.

BUT: why does the same amount of water weight more, just for having increased the distance between molecules, due to the temperature?????

Heat places the matter in heighten state that makes the matter more acceptable to the potential of the gravitational pull.

like ahhhhh, Plasma?

Well air is matter.

According to your colleague, it weighs less.

I think there must some sort of goofy trick at play here.

The beaker is completely topped off with 25 °C water and the total weight of beaker and contents recorded as X

The beaker and water contents are heated to 60 °C. and after cleaning up all the spilled water that overflows the beaker, the result should be a lower weight reading, not a higher one. (Water expansion coefficient is considerably greater than that of the glass beaker).

One experiment is worth a dozen hypotheses -- I'd tell her to weigh the solution while it's hot then wait until it's cool and weigh it again. Make her demonstrate to herself that in this type of scenario weight is independent of temperature.

Many people are vaguely aware that air is 'heavier' or 'lighter' depending on whether it is cool or hot, and they incorrectly infer that this applies to all liquids and solids as well.

What I actually told her is to warm up the liquid to be added to the same temperature of the "mother" solution. and to proceed as normal.

But the issue here is what the heck happens to weight of matter when it gets hot! (pardon my french)

Nothing happens to the weight. The volume expands with heat.

If matter weighed more when it got hot, "hot air" balloons would not float.

I fully agree with you.... but not my colleague!

What we have here, is failure to communicate.

Apparently all logic and reason have been educated out of her brain.

Even if air weighted more when hot, it's huge expansion makes it much less dense than the surrounding air, thus causing buoyancy or flotation.

The heated air has less density. That's where you get the expansion. Not that air molecule weighs less. Just not as many of them on the inside of the ballon as on the outside per a volume.

And that is the difference between ACFM and SCFM when working in HVAC.

Hello r&ddoc:

You have many options, here's some of them

1.-Let her prove herself wrong.

2.-Stop preparing deserts while at the lab.

3.-If you guys must have your gelatin, bring it already prepared from home.

4.-You can change to candy bars, like everybody else.

Try this, it will save you all the arguing once and for all:.

1. Weigh a new bag of pop-corn.
2. Microwave it and observe the expansion of the mass (~78-83 times than uncooked -yes, I was surprised too-). Note the temperature rise as well.
3. Now that you caused very noticeable physical changes in its contens, carefuly open the bag, give a damn about everything and enjoy.

Hello amigo! I followed your idea and made some pop corn: the cold bag of unpinned stuff weighted 130 Gramm.... and once ready, and damn hot.... 130 Gramm. After cooling down weight was just the same.... In this case the theory of mass and gravity did not work! :-)

Hi! I agree with you about density, but we usually work at 21ºC, and depending the process we are doing we measure using both (weight and volume) methods. In this particular case, which was a test "just to see what happens" I needed a lees dense jelly than what we hat at 60ºC. The quick way of dissolving it was adding more water. Due to my impatience, I just wanted to use a little amount of cold water, proposed her to weight both (jelly at 60ºC and water at 21ºC) to determine what proportion I was about to add. Here is where she came up with the "theory of the weight increasing with temperature" I´m not gonna buy so easily! The Jello we use is unflavoured and can be eaten if prepared in a proportion of 5 to 10% in water. The way we do (30%) it smells like a bear in heat..... Next we will do some candy with the unused jelly... but that will probably be the subject of another post ;-)

Well if you're heating the fluid you're adding energy, so there is a slight increase in mass, about 1.11×10^−17 kg of mass for every joule of heat added to the water, and with heating the volume also increases...Probably about the same effect as lowering the water from the stove height to the floor, as gravity increases as you approach the center of the Earth... weight is a figure arrived at by multiplying mass by gravitational acceleration(F=ma) force is equal to mass times acceleration...What she was probably referring to was the volume had increased, throwing off the measurement..as the density had decreased...such that the same volume originally used for the measurement was no longer valid....

She may be right (at least she has more scientific credits than me, being a Neurosurgeon)... but the difference in weight she refers to is less than insignificant if considering the background of this "experiment"

I would have to agree in this context the weight is more theoretic than the heat which might effect the outcome due to the sudden change in temperature...but I'm not much of a cook so I couldn't say with any certainty...perhaps we have some jello experts that could shed light....

If she is so persistent on her misaligned theory, one that is shown to be incorrect in jr. high school physics or sr. high school chemistry or college freshman chemistry/physics, how is she supposed to make other decisions in the lab? Very important ones such as: to operate within the cranial cavity or give medication; scalpel or hacksaw; blood or platelets; red or pink lipstick; pumps or high heels; beaker or flask; light and sweet or black; text or e-mail; common sense or erratic confusion; elevator or stairs; and many numerous other timely and significant matters?

Good Luck, Old Salt

How would you propose to weigh the miniscule weight change, if there is, indeed, any?

Mathematically...

From ridiculous to sublime.

We're not measuring atomic weights and energy levels, we're measure liquids.

Maybe a precise amount of heavy metal(s) were/was added to create a special growth medium....and adding more water would breach protocol...

http://www.pbgelatins.com/about-gelatin/physical-and-chemical-properties/solubility/

http://www.microbelibrary.org/library/laboratory-test/3776-gelatin-hydrolysis-test-protocol

Hot woman weigh less. I totally agree with your colleague.

CR4 needs a third rating category, i.e., a "GOOD Off Topic ANSWER".

Your experiment as elementary as it may seem will not demonstrate any change in weight. As the weight add by heat is in the nanogram range. Also will be some losses to the open can which would be in that range.

Wasn't the whole idea of the ops posting supposed to be that there was no change in weight of the liquid as it is heated? This part is open to commentary from others.

There should be no change in weight added/deleted as the liquid is heated or cooled. Any losses due to the can being open in that range will be miniscule (smaller than a gnat's a$$) since the beer can is too large to be weighted on a lab bench Mettler's balance. A bathroom scale, with the liquid contained either in the original closed can, the opened can, or the new container the stomach, could be used but is not accurate enough to detect this miniscule a loss.

Since the experiment will surely have to be repeated numerous times, I would suggest a pallet size floor scale with load cells be used. This could then accommodate the more rapid testing necessary when the whole lab is asked to participate in the testing of the whole pallet of test material. If she can't be convinced by one person's explanation then gang up on her and have the whole lab convince her.

Invite the whole CR4 group for the tests and they should have the Lab Supply dept. running out for more samples very quickly. With the numerous interests in engineering and science among them, they surely will have an accurate answer after 4 pallets and about 3 hours.

If I am present it might take a whole lot of testing to buy my vote! (I prefer mine cool, not warm)

Good Luck, Old Salt

An open can of ale/malt liquor will loose mass over time from the dissolved carbon dioxide escaping to atmosphere: alternate experiment would be to take the same sealed can and determine mass at two different temperatures to show the mass is same. Looks like most are confusing mass with density with regard to change in temperature. Mass does not change with temperature until you get into the realm of relativity (close to the speed of light)

We were doing our lab test on a hurry, so we may have done it at the speed of light without realising it!

Lorentz invariance

The world is not invariant, but the laws

of physics are!

WP

You don't need her to do any experiments. Just ask her to show you the formula, either chemical or physical that confirms that weight is temperature dependent. When she fails point out that as no other chemist or physicist has yet noticed this phenomena, and that as it is so significant, she is obviously going to receive a Nobel Prize for this discovery. Request a ticket so that you can be present when she is awarded the prize, and keep on asking for your ticket for the next six months. She will soon become so annoyed at you making fun of her in front of your other colleagues that she will admit her error and apologize just to shut you up.

It could weigh more hot because energy has mass (weight), m=E/c². On the other hand, it could weigh less because the liquid expands when hot, displaces more air, and so becomes more buoyant in the atmosphere. I suspect neither effect is easily measurable.

Ask your colleague what is her weight when she is normal and when she is angry?.

She will be angry when she weighs more!

If she is your " colleague " , why would you be " arguing " with her ? Are you sure she's not just an " employee " and your not her boss ?

And if she's got a degree and all that other stuff, then when, is she going to post a comment ? ; and then we all can hear her take on this discussion.

This is quite a democratic company, so there are (besides the owner) no bosses.

I tried some sweettalk to get her posting her opinions about this subject .... no success so far

Depends on how you look at the quantity. 1^3 inch of material will expand with heat, some will be out side the 1^3 inch volume, therefore what is in the 1^3 inch will weigh less. X amount of mater not, considering the volume, will change size when heated, but since, in this case the size is not considered, it will weigh the same. Consider gasoline in an underground storage tank. When the fuel is cool, a gallon is pumped, it contains X BTU. When it warms up, it gets bigger, less dense, so a gallon is still a gallon, but has less BTU. -- My take on it with my uneducated brain! -- JHF

That is one dumb bunny!!

As long as the liquid is not losing volume by steaming or similar, it won't get lighter, BUT it also won't get heavier as it cools from the hot weight in say a closed vessel.....

She is probably one of those highly qualified "parrots", who "know" stuff, but do not "understand" stuff.....its sadly common!!

You might be able to rig a test, suspending a container of liquid over heat from a spring balance....heat it up, let it get cold, it may lose weight, but it will not gain any just by cooling!!

She obviously was out with her boyfriend when volume and temperature and density were discussed!!

<UNSUBSCRIBE>

This is her reply to our comments:

A: room temperature

B: 50ªC

What did it weigh cold afterwards?

That could be the clincher....

It appears (being politically correct) that she has only done part of the tasks to substantiate the weight loss.

What is the weight of the liquid after cooling back to room temp, remember the beer cans? If her 'loss due to heating' theory is correct there should be a return to the original weight upon cooling. If the loss is due to vaporization, the weight will stay the same as the heated weight or even less.

If materials were to loose weight upon heating, why don't solids loose weight upon heating? Have her weight and heat some coins or other metals from Rm Temp to the same temp as her previous experiments. Weigh them, cool them and weigh them again. If she insists on continuing her "theory" go to a higher boiling point liquid such as Castor Oil, with a boiling point of 313^oC. Do it with that and have her see that there is no loss in weight. If very dry (low in water moisture) castor oil is used it may even pick up a few milligrams upon heating.

If it goes any further than this: 1) use a closed beaker by placing a rubber glove around the top, as an expandable lid, with a rubber band holding it in place. This will seal the beaker but not allow pressurization. 2) hold a piece of glass over the beaker as it is being heated to show condensation of any vapor that was "going into the wind" on her previous experiments. This is where her weight loss was coming from. 3) Go back to the beer, ale or malt liquor laboratory experiment with numerous laboratory personnel testing. It won't get an answer any more incorrect than what she is now doing and it is a lot more FUN. 4) Have any of her coworkers ever accused her of being stubborn or "fudging" her results?

Good Luck, Old Salt

You can see the water vapor accumulating on the side of the glass in the heated example, this would clearly indicate that there is vapor escaping to the atmosphere because the glass is open to the room....This is loss of quantity of water, so you're comparing apples and apples with a bite missing...

Hi r&ddoc

All specialis in balances know that: a temperature gradient between the weighing and the environment caused
air currents along the weighing container. Rushing air
the container generates an upward or downward force.
The weighing result differs because of the correct value. This effect is
called dynamic buoyancy. It decreases only after it has
thermal equilibrium established. It is true: a cold object appears
heavier, and more like a warm light. This effect can cause
problems, especially in heavy differentials semimicrobalances,
microbalances.

WP

doc: It is the volume of solution (based on a general assumption of minimal to no evaporation loss) that changes (for the larger) with temperature. There might be something "jikky" with the lab balance if one cannot assess mass of hot objects without introducing a large error.

Density is the only thing that decreased, not the actual amount (mass) of the water/gelatin mixture present. Apparently, your assistant is suffering from her present curse, and best to be left alone for now. A four hour argument is not worth it, since the thing could have easily been cooled off, added to and reheated by now.

James, a four hour argument is what makes fun when working at our lab when it comes to discus about experiments we are conducting. Together we are a great team, cause she has been educated in a "hard" science, and me in a profession (I do not dare to call medicine a science) in which 2 + 2 is usually not 4. Each of us has specific duties, but when it comes to work together I often provide creativity or a view from an unusual angle, while she tries to turn my madness into reproducible phenomena... and when such a thing happens she has turned it into a scientific method. So far we have reached a truce at our lab: measurements will only be done at room temperature. Both have reached a pyrric victory.... as the two of us know the other side is WRONG!

More pyrotechnic than pyrrhic, I feel

As to the experiment: go back to the start, and use a closed container (sealed), and only heat it to 60 C for the second weighing. This way, the first room temp weighing, and the final weighing should be within the margin of error, along with the second one that is the same weight., unless you do not take action to rule out air currents by evacuating the lab balance to null pressure, you can do that can you not? If not, then you must preheat the balance chamber with a warm air gun (as long as you do not damage the balance).