# Homework Help: Thermodynamics Problem

1. Jan 31, 2009

### haydn

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

MI kilograms of ice is placed into a MG kilogram glass container holding MW kilograms
of water. The water and the glass are initially at 25 degrees C. If the ice came from a freezer at - 15 degrees C, what is the final temperature of the drink assuming that there is not enough ice to freeze the water?
You are given:
LV for water
LF for water
Specific heat of water is CW
Specific heat of ice is CI
Specific heat of glass is CG

2. Relevant equations

Q=mc$$\Delta$$T
Q= + or - mL

3. The attempt at a solution

I know that when the ice is placed in the glass container holding water, all three will transfer energy and reach an equilibrium temperature. I know to set up the equation using:

Qcold = -Qhot

With the glass and water being the "hot" and the ice being the "cold." The loss of heat of the hot is equal to the gain in heat of the cold.

I know Qhot will be equal to mc$$\Delta$$T for the glass and the water.

What I'm not sure about is Qcold... I know it will increase in temperature so I need to include an mc$$\Delta$$T, but how do I know whether or not it is going to pass 0 degrees C and undergo a phase change to liquid?

Thanks.

2. Jan 31, 2009

### davieddy

The assumption in the question implies that all the ice gets melted,
since the final temperature > 0 degrees

3. Feb 1, 2009

### haydn

Ok, so will the Qcold expression include mL and mc$$\Delta$$T or just mL? And please explain why...

Thank you.

4. Feb 1, 2009

### davieddy

Heat gained by what starts as ice = heat lost by drink + glass