# Phase Change

1. Feb 11, 2009

### veronicak5678

Hoping someone could double-check for me....

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

1) A 90 g block of unknown metal is heated to 86 degrees C and put in an insulated cup with 175 g water at 23 degrees C. At equilibrium, they are both 25.8 degrees C. What is the specific heat of the metal block?

2) A well insulated cup contains 145 g of ice at 0 degrees C. We pour in 45 g watwer at 75 degrees C.
a- Once equilibrium is established, how many grams of ice remain?
b- What is the final temp in the cup?

3. The attempt at a solution
1) c ( 90 g) (-60.2 degrees c) + 1 cal/g degrees C) (175 g) (2.8degrees C) = 0
c = 0.0904 cal/g degree C

2)
a- energy available to melt ice: 1 cal/ g Celcius (45 g) ( 75 degrees ) = 3375 cal
energy needed to melt ice: 145 g (80 cal/g) = 11600 cal
not all will melt

80 cal /g (mass melted) = 3375 cal
mass melted = 42.19 g

b- Temp is 0 since there is still ice.

2. Feb 11, 2009

### Delphi51

Looks good to me!

3. Feb 12, 2009

### veronicak5678

OK, great. Thanks for looking it over!