Science aficionados please: Does boiled water weigh more? What scientific principle is at play here?

Question

This is a dumb question, but I've been wondering it for a while. These unanswered things are like itchy sweaters to me.

Every morning I get up and put on this kettle to boil water for some coffee. I try to fill about the right amount for just 2 mugs of coffee (one for me, one for my husband.) This kettle is high quality stainless steel, gets nice and hot very quickly. But... it's heavy, so I don't want the kettle to weigh any more than it needs to.

My question is about the perceived weight. When the water is boiling (not just a low simmer, but a rapid boil), the kettle always feels significantly heavier. Is this possible at all, or is it my mind or body playing tricks? Does the agitation of the water do something to the perceived weight?

I know almost nothing about scientific principles; yet problems, or questions like this can sit in my mind and I think about them every time I'm in the situation again. I've been experimenting for months with this, changing the hands I use to lift the kettle, both when I first fill it from the kitchen tap, and when I pour it once it's boiling. (My left wrist tends to hurt, in general, because I hold my cell phone in that hand almost exclusively and I'm pretty sure it's got carpal tunnel now, so this whole thing is not because I'm using different hands before and after. I use the same one hand (sometimes the left, sometimes the right.) I've even tried using two hands to lift.

No matter what I do, I feel like the kettle weighs more later, on boiling.
Once I do the first pour into the filters, walk away, come back to fill the second time, I easily notice a difference in weight.
So if the heating and agitation of the water creates [what? instability or something?], is it real or perceived, and what's the scientific name, or principle, associated with that? I'm just curious. (We could use more science and learning on GAG, no?)

invalid1 · Accepted Answer

I TRUST you will understand me.
When you heat the water you increase something scientifically called ENTROPY.
Stephen Hawking defined it in one of his equations, I can look it up in google if you want me to.

So the force of gravity exerted on your hand by the weight of the kattle and the water it contains, by the sum of the mass [is what you referred to as weight]. This thing doesn't change, even if it does, it's not significant. In fact the kattle is supposed to weigh less after boiling because the water is evaporating and losing a portion of its mass.

But what I think you're describing if I can use my experience in such observation, is that you find yourself having to use more force after boiling. Because the water is not static. its particles are moving in a circular direction, or chaotic direction, adding tiny force to that of the weight as it moves against the force of your hand.

I could be wrong though.

😂 Too much explanation for such observation. lol! I got C- in my thermodynamics 😩

DamnSam · Accepted Answer

I think there our mind gets tricked bc the kettle is actual more full when it boils but the weight is the same

Because the volume increases at higher temperatures until it evaporates... with every material, not just water

And since the higher water producing a higher weight point, it feels heavier...

You can also see it if you fill a cup with steam hot water, mark the top of the water and wait until it's cold, the water will shrink about a half inch, even if you close it airtight...

Science is sometimes strange
If you mix 1000ml pure water and 1000ml pure alcohol, you get out 1997ml because in the alcohol molecules is space for water molecules...

Fireguy17 · Answer

This is fairly easy to prove.
Weigh the kettle with cold water, then heat the water and weigh it, my guess is that it will weigh the same.
Now as you heat the water it will expand by volume because it is hot, but heat rises because it is now lighter.
Same with air, hot air rises, like how a hot air Ballon.
Your hot water heater is a good example of how this works.
The hot water is drawn off of the top of the water heater, and the cold water that comes in to replace the hot water comes into the bottom of the water heater.
It can look confusing if you just look at it because both pipes are on top, but look up a cross section of how a hot water heater works.
An other way to look at it, and divers can attest to this is the thermal climb in a lake.
As you go down in depth you will find where the warm water is sitting on top of the cold water.
It can be a big change.
The top layer may be in the 70s or warmer, the cold water can be in the 50s or even colder.
That is why you see divers with hoods on, full wet suit and gloves dressed like that even on a hot summers day.
I live in Wisconsin and it can happen around the 15 to 20 foot range, but every lake is different.
Also in spring and late fall before it freezes over, the water will actually rotate, where now the top layer is now colder than the water below so it sinks and the water at the bottom rises because it is warmer.
If this happens quickly the lake will have a different smell to it for a bit because of the change.
I could smell it once in a while on the lake I used to live on.
Many years it would happen gradually and I wouldn't notice it.
I always liked science and physics, it explained how things worked and why.

FilmGuy93 · Answer

Temperature doesn't make something heavier, no.

In terms of perceived weight, if your arm can't exert force effectively, objects will feel harder to lift because you can't put your full strength into lifting them. So it's like how mattresses are a pain to move. It's not because the mattress becomes heavier; it's because it's difficult to get a good grip.

So as far as boiling water goes, your hand might not be comfortable with the heat from the kettle, so your arm isn't able to put as much strength into moving the kettle.

ohshee · Answer

Cool water should be heavier as the hot water boils the molecules probably get closer together cold weather gets more denser
Okay so check this out did you know water was our very first computer water holds memory if we were to get a glass of water and get one of those little eye droppers you hold onto the glass of water Phillip your eye dropper and put it on a piece of that microscope glass and put 10 drops on it alternator drops would have the same identical snowflake that's your identity you hand me the glass of water I take the eyedropper and do the same thing I will have my own identity the same snowflake out of 10 drops of water we don't even know how important water is if water can hold memory like that and remember who you are to me that's a trip that is so cool that's almost like a god

Mango-man · Answer

It isn't heavier.

Hot water has lower density that cold water (max water density is at 4°C).

However the feeling of boiled water being "heavier" could be simply due to the movement of water. Cold water just sits still, but boiling water moves around inside the kettle, which puts a bit of extra strain on your muscles to keep the kettle stable.

krin_m · Answer

Here is some explaination:

exitseven · Answer

Boiled water actually weighs less per unit volume. As it heats up it's molecules vibrate faster and the water expands. If the water is in a teakettle then the weight will stay the same discounting the water that escapes as steam. It just occupies more volume within the teakettle,
Ironically, water also expands as it freezes. It does this because the molecules are slightly charged at the ends and attract other molecules and upon freezing form a crystalline structure that takes up more space.

Surely · Answer

Not being a science nerd. Since water expands when heated. I would say hot water by the same volume as cold would be lighter in weight. Probably not enough to be noticed by human hands.
That is why they weigh gas tank trucks to get an accurate volume of fuel. Hence, why you should gas up when the temp is cooler instead of the heat of the day!

iWantToCry · Answer

Is steam the same weight as water? The mass of 1 kg of water at 70 F and 1 atm and 1 kg of steam at 212 F and 1 atm is exactly the same. The volume will be significantly different. About 1000 x different. Weight is force and the weight will be different due to buoyancy.

Avicenna · Answer

Water is measured in volume, but when it's heated, it's density decreases and it weighs less (molecules aren't as close together).

Pete671 · Answer

Minus a loss from evaporation, no it would weigh the same, maybe feels heavier because it's hot and could scald you, so you're cautious about handling it which takes more concentration,,,

Neosporin · Answer

My guess is because it’s boiling the water is thrusting about and that thrusting activity is perceived by your hand as extra weight.

scooogy · Answer

Provided that it stays encased in a pot or something, from a strict view its state only changes in volume or pressure against the encasing medium.

This_Is_My_Opinion8 · Answer

"Does the agitation of the water do something to the perceived weight" Bingo!

sattii2607 · Answer

As long as no water escapes as steam the weight remains the same but volume will increase.

genericname85 · Answer

Probably yes, cause the concentration of "non water contaminants" becomes bigger as water evaporates. But it's probably a tiny amount.

Snakeyes7 · Answer

I'd imagine initially it would weigh the same as if it wasn't boiling but over time it gets lighter because of the steam escaping. Not a scientist but thats my speculation.

Andres77 · Answer

The scale burns up every time I try this so...

noohair · Answer

The water expands and evaporates when heated. The same volume of cold water will weigh a little more that the same volume of hot water due to density.

Ad_Quid_Orator · Answer

in my opinion the steam escaping from the top is creating a force pushing downward on the kettle making it feel heavier.

Kelly6 · Answer

I think gas is loa locked in it and makes it heavy, when it cools down gas is gone

Science aficionados please: Does boiled water weigh more? What scientific principle is at play here?

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