[ajax0604]

My friend and I are in disagreement regarding the effect on heat loss when you use calorimeters with different heat conductivities.
All variables are same except for the substance making up the container which holds the water. One is aluminium and the other is asbestos (which has much lower conductivity). Both are heated up by the flame from a spirit burner until a temperature change of 20 degrees is achieved.
I believe that the more conductive aluminium will transfer the heat to the water more quickly but due to its higher conductivity, the heat loss to the surroundings would be greater.
On the other hand, my friend believes that aluminium is much better at conducting the heat from the flame to the water so overall, the heat loss would be less.
Could someone help?

 

[Borek]

It is not clear what the question is, as the description is quite ambiguous.

What is the exact scenario? There is some water in a vessel, and this vessel is heated up by an external source o heat till water temperature grows by 20 °C, yes?

For starters - that's not what calorimeters are designed for and this is not the calorimeter, but just a pot or kettle

But the most important problem is: what you mean by "heat loss"? Where does the "lost heat" come from? Is it the heat from the burner? Or heat lost by water during heating? Note, that the latter is a rather strange construction, water heats up so technically it is not loosing any heat, quite the opposite.

So, can you elaborate on your experiment and precisely define what you mean by each statement?

[ajax0604]

Sorry about the ambiguity.
The purpose of the experiment to heat up a fixed volume of water in a container by combusting an alkanol in a spirit burner.
The container is just that, not a proper calorimeter.
By 'heat loss', I was referring to the heat that escapes to the surroundings from the water through the walls of the container since the container is not insulated. If the substance of the container is changed, would that make any difference to the percentage of heat lost through the container?

[Borek]

As I wrote - it doesn't make much sense to speak about "heat loss from water", when the water is gaining heat.

Basically the only thing that can be reliably done in your scenario is estimation of how much heat is lost from the whole system (heater/container/water) during the heating. Assuming the burner produces heat with a constant speed (that is, works with a constant power) the most important factor is: how long does it take to heat the water? That's definitely where the container material (and its properties) becomes important (but you should be easily able to predict what to expect).

[Arkcon]

Just like Borek:, I'm having a little bit of trouble figuring out why you're asking the question.  Let's try to think about some things that would be useful for you.

Typically, when a beginner student is doing calorimetry, the use some sort of insulated container.  Even a typical Styrofoam coffee cup, or better yet a doubled one, is just fine for this application.  I can only guess -- this is done to avoid loss of heat from the water before measuring.  SO if you have a heat conductive vessel, you won't have that benefit.

Thing is, a bomb calorimeter is often made of steel.  We know there's going to  be some heat loss from the water, but if we know how much, we can just compensate.  Like Borek: said, (I think) we don't care about the water's temperature over time, instead we want to know how hot it gets, so we know how much energy was transferred.