For Water That is Being Heated...

Depends strongly on the ambient temperature, and insulation of the container. In most real situations, heat transfer between the volume being heated and the surroundings will be the dominant factor.

It doesn't matter.

A BTU is a BTU no matter the temperature.

Keeping in mind what JohnDG said about heat transfer, look up the value for your container and factor that into your calculations.

Oh, look up BTU, also.

DO YOUR OWN HOMEWORK.

I hate to be contrary (), but why is a calorie defined at specific temperatures ? Never thought to ask that at school .

You're asking me? I'm the one who just proclaimed (wrongly, I guess) that a BTU is a BTU.

Allow me to speculate that because with added heat comes wider separation of the water molecules (expansion and all) making heat transfer ever so slightly less efficient?

That must (somehow) overcome the added molecular excitation caused by the addition of said heat energy, be it a calorie or a BTU.

I was sick the day we covered that in school.

No, you are not allowed (as if I could stop you), it's a BTU. Until you lot can go metric, much as I like to rag the Frenchish, you are hardly able to comment on the topic .

The best you came up with was sick that day ? The only reason I got thru Skool was that the teachers wanted to get the hell rid of me.

Metric you say? Balderdash, I say!

Who in their right mind would give a flying petunia about warming one gram of water to any temperature? What in blazes does one DO with one gram of water anyway?

Metric is no friend of mine! Because of it I have to buy two sets of wrenches, two sets of sockets, two sets of Allen wrenches and I can't even buy a quart of Bourbon whiskey any more.

Next thing I know they'll have metric shot glasses in bars. I can just hear it now, "Bartender, give me 473 cc's of Guinness and 29 and a half cc's of whiskey back, neat".

John Wayne will turn over in his grave.

No, wait! Don't you Brits still order stout by the pint? Pint? What kind of metric measurement is that??????

We are still "two nations divided by a common language".

If I was not totally pissed (and I am), I'd slamdunk you. I think I spelled that wrong (acc to CR4 spellchucker). May I return later with a witty rhetort when I can see my keyboard ? Dil tort mi evurythung i nu about intaweb.

Alright, that was a 'gag'. I shall go to bed and be on my best behaviour*.

_{* Not much of a promi8se but.....l}

We have a special dispensation on pints (of liquid comestibles). A pint is a pint, dammit! One goes to the pub for a pint. End of. We can also by a pint of prawns, winkles, or various other shellfish. But a pub (or a fishmonger's) is not a laboratory, workshop, construction site or space centre.

To the both of you.

Since I consume Guinness whenever I'm in a pub that has it on tap, I'll not whine about that.

But, what does burn my butt is when some little tart behind the bar tries to pour a pint, without the head.

I watched some honey pour out half a glass, a bit at a time, trying to get the glass full without the head. I didn't bother to correct her, she'da just thought I was a stupid old man.

Sad, that. I have similar problems with ale, occasionally.

Go sit in the corner of shame ! Guinness is just about OK, but experience tells me that a 10-pint session is not good (been there, done that ). If you want to try that direction, use Theakston's Old Puke.

Don't tell anyone, but there are a few bars over here where you can get the head exactly as you like. My younger sibblings once dragged (bad choice of word) me to a club one night. It was possibly the funniest night out I have ever had.

I have absolutly no idea why I have rambled in this direction. A fairly straightforward question, and I'm completely OT about it all. kaplin made me do it (you'll have had to see the blog/post to get my naughty innuendo)

I drink from bottles, mostly. Unless by the pool. Cans can be contaminated by stray cats, (not you Del) and bartenders have been know to give me glasses with lipstick on them that is not my shade.

But, when I drink Guinness, I like a healthy head and I like seeing the bubbles running DOWN the inside of the glass.

At my age, I've gotten over wanting the glass filled to the brim and had rather have a friendly, attentive bartender who doesn't let me wait for the next one. Better yet, one that knows what I drink as soon as I walk in the door and has it waiting for me.

I learned something in a cooking class my daughter talked me into taking. Water molecules being polarized tend to clump together with the negative oxygen atom sticking to positive hydrogen atoms of other molecules. The high specific heat of water is mainly due to breaking these hydrogen bonds between the water molecules.

Because the specific heat of water varies slightly with temperature. But you'd have to be doing very precise work for it to be significant.

This is due to the slight changes in specific heat as temperature is changed to the boiling point from the freezing point, and upwards to the critical temperature. There is a standard state definition for every physical unit we utilize. The meter is only a meter (if it is a standard bar) at a certain temperature, and so is the wavelength definition of the meter, accurate only when the determination is carried out at a specific and controlled temperature in the testing laboratory.

NOW TO THE OP: GO DO YOUR OWN HOMEWORK, SOME OF US ARE BUSY SOLVING THE WORLD'S PROBLEMS!

Making reasonable assumptions, no we don't

Specific-heat capacity decreases with increasing temperature, which means that when you add heat energy to warmer water, the temperature of the water will increase more than when you add the same amount of energy to cooler water.

How, you asked? Vibrational states of water molecules mainly, their great heat capacity (approaching the theoretical max) thanks largely to their hydrogen bonds and consequent vibrational modes. Also look up Frankel's and subsequent theories concerning phonons and shear modes (yes, in liquids. Imagine that).

Now if you really want something to boil your noodle, stars get hotter when they radiate energy away into space (why? It has to do with gravity and what lots of matter does in the presence of lots of gravity) and, when you add mass and energy to black holes, they get colder. Negative heat capacity.

Is this part 2 of the specific heat question????

Laying one's hands on a set of Steam Tables would mean never having to ask this question again. The information needed is in the public domain.

With no information on the ambient temperature, the units of measurement or the level of insulation of the container, the question is unanswerable.

If you are talking about the normal way we heat water in an open vessel, it will take more time to heat the water to a higher temperature, per degree, due to the losses produced by the water delivering its heat to the surroundings.

In general and in everyday experience, this is true; the greater the difference in temperature between an object and its environment, the greater the rate of heat transfer to (or from) the environment.

Thing is, the OP said it takes less time to raise the warmer water's temp through the given range than it does the colder but, as you pointed out, in the case of the heated volume dissipating its heat energy to the surroundings the opposite is true, so what must be going on?

The OP noted that the warmer water heats faster than the cooler, and so what mechanism might explain this? Evidently the mechansim of a change in heat capacity over temperature. A homework problem, no doubt, because in Real Life the heat loss to the environment would generally swamp the effect of a change in heat capacity. It's there but, for all practical purposes, 'buried in the noise' of everyday experience.

"Thing is, the OP said it takes less time to raise the warmer water's temp through the given range"
No, he didn't.

The way this is going we'll be discussing which freezes quicker in a freezer, hot or cold water? The Mpembe effect, if memory serves, that we spent time on a couple of years back. I remain unconvinced the effect is real.

Me, too. I tried it using Al mixing cups and the cold water always froze first.

Hey, this is better than answering lame questions about wire sizing or defining MCCB for some loser.

Dear Mr.Kokate,

You have not mentioned about the lagging aspect and other details.

When the temp. is higher, if lgging is not proper, the heat loss due to radiation, will be higher, and will absorb more heat, and hence it will take more time.

Hence heating from 30 to 40 will be quick with less energy than heating from 40 to 50 Deg.C.

DHAYANANDHAN.S

The hapless student is doing theoretical homework.

This is not a practical problem. All variables are ignored.

Therefore, the student is ignorant of the real world.

For one thing, THE SYSTEM is an undefined global, therefore this question does not compute!

If it is being done in Fahrenheit degree, it will take much longer from 30 to 40 since it has to overcome the latent heat of fusion. -- JHF

Yet another unknown.