# Homework Help: Ice cube melting, solving for Initial Temp of Ice.

1. Mar 18, 2012

### Skeetss

1. The problem statement, all variables and given/known data

.019 Kg icecube @ unknown temperature (In deg C)
Placed in 200 mL (.2 KG) water at 35 C.
After melting, water is at 22.4 C.
Find initial temperature of ice using conservation of energy.

2. Relevant equations

I've done the math a ton of times and keep getting -60 C which is completely unreasonable seeing as this was an incube taken out of a standard freezer.

I'm using the equation:

$-mC\Delta T_{water}=mC\Delta T_{ice}+mH_{F_{ice}}+mC\Delta T_{water(ice)}$

HF= Heat of fusion of water/ice

Plugging in for ΔT, I get:

$-mC(T_{F}-T_{I})=mC(T_{F}-T_{I})+mH_{F_{ice}}+mC(T_{F}-T_{I})$

$-.2(4180)(22.4-35)=.019(2080)(0-T_{I})+.019(3.34*10^{5}+.019(4180)(22.4-0)$

$T_{I}=-60°C$

That can't be correct.

Any help would be greatly appreciated. I'm sure it's my math somewhere.

2. Mar 18, 2012

### Staff: Mentor

I can't spot any errors in what you've done.

If this is data from an actual lab experiment can you identify other sources or sinks of heat energy that might have interfered? For example, what about the container? What was it made of? How was it insulated? How long did the mixture have to sit before taking the final temperature?

3. Mar 19, 2012

### technician

Agree with the answer. I agree that it sounds extreme but it is not impossible !!!!!!
It is a 'tiny' piece of ice compared to the mass of water and the temp change is 'quite large'

4. Mar 19, 2012

### Skeetss

It was a styrofoam cup so it was insulated pretty well. My guess is my labmates misread or interfered with the final temp by accident. We were looking to find the initial temp of the ice and the lab question was to find the temperature of the physics department's freezer so who knows what went wrong. Thanks for the help.