- #1
sunquick
- 18
- 0
Homework Statement
A quantity of water in a beaker of negligible thermal capacity is cooled to a few degrees below freezing point. The beaker is then placed in a warm room, and the times recorded at which it is at various temperatures as it gradually warms. The observations were:
temperature/ºC time/min:
-3.0 0
-2.0 0.93
-1.0 1.89
0 2.92
...
0 169.72
1.0 171.84
2.0 174.04
3.0 176.34
Homework Equations
[tex] Q=C \Delta T [/tex]
[tex] Q= L [/tex]
[tex] Q= P \Delta t [/tex]
The Attempt at a Solution
My question concerns part b)
I assume the power delivered to the system is constant.
So [tex] Q=C \Delta T = P \Delta t [/tex] or
[tex] \frac{\Delta t}{\Delta T} = C/P = const [/tex]
So I fit a straight line to the experimental points to determine the slope and so to know C/P.
There will be two heat capacities, one for ice and the other for liquid water. I can determine the ratio o C_ice / C_water, and also of the latent heat necessary to melt the ice by noting that
[tex] P \frac{\Delta t_1}{\Delta T} = C [/tex]
[tex] P \Delta t_2 = L [/tex]
[tex] \Delta t_2 \frac{\Delta T}{\Delta t_1} = L / C [/tex]
I can find the heat capacities and latent heats with respect to one another, but I can't seem to know how find one of them in "absolute terms". My question is if that is possible, and what other quantitative results can be obtained from the observations?