# Homework Help: Thermal Equilibrium and Energy System/Phase Diagrams

1. Jan 18, 2010

### elissa5

1. The problem statement, all variables and given/known data
A 0.5kg piece of ice(water) at an initial temp of -65 degrees Celsius is placed inside a well-insulated container with 3.0 kg of tea at an initial temp of 20 degrees Celsius, and the two are allowed to come to thermal equilibrium( the tea can be treated as water with respect to thermal properties)... they want me to draw a energy system diagram to show this using ethermal and Ebond and figure out the thermal equilibrium?

2. Relevant equations
Ethermal= mcp(tf-ti)
Ebond= delta(m)delta(h)
mass of ice= 0.5kg
mass of water= 3.0kg
heat of ice/water/watervapor= 333.5 kJ/kg
specific heat of ice 2.05 KJ/kgK
specific heat of water 4.18 kJ/kgK

3. The attempt at a solution

1. The part im mainly confused about is i know we have to figure out delta(m)delta(h) for ebond and i have the solution saying that delta m is .5 and delta h is 333.5= 166.7. I understand how they got delta h but im unsure of how they got deltam to be .5?? Another thing is i know that we have to do mc(tf-ti) for tea which is (3)(4.18)(0+20)=250.8 and we do the same thing for ice which is (.5)(2.05)(65)=66. But whats the point of figuring out all these numbers....how do we use these to solve the problem (it has to do with phase diagrams but not sure how)??

Sorry i know this problem is kinda long. But any help would be greatly appreciated! Thanks! The solution from the book states Te= 1.19.

Last edited: Jan 18, 2010