forgot!  - sign of course, exothermic. 

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<o:p> </o:p>

OK how about another problem<o:p></o:p>

<o:p> </o:p>

On a visit to the <st1:place w:st="on">Midwest</st1:place>, you find yourself in a freak hailstorm and get hit by a 6 pound piece of hail  You really want to keep this ice chunk as a souvenir so you decide to pack it in dry ice, put it on the plane with you, and stick it in your freezer.  Unfortunately, you only have a frost-free freezer at home.  How long will the piece of hail last (start the timer from when you get bonked on the head in <st1:State w:st="on"><st1:place w:st="on">Iowa</st1:place></st1:State>).  There are lots of different variables to consider so you can do a lot with this problem!<o:p></o:p>

The molar heat capacity of ice is  37.6 J/mol -*C<o:p></o:p>

I figured this to be 6 lb ice ball to be 2721.54 g and 151.06 moles of water.  I am saying the outside temp is -10 C and it took me an hour to pack it in dry ice so I guess it would still be ok?<o:p></o:p>

I think I can get it home without losing any of it to melting.? <o:p></o:p>

so 151.06 mol  x 37.6 J/mol - *C = 5679.86 J/*C  ????<o:p></o:p>

How would I calculate the kJ needed to melt it without a temp change?  I need to know that don't I?<o:p></o:p>

I am still pondering. <o:p></o:p>

 I am thinking the frost free freezer is the key.  Any insight so far?  <o:p></o:p>

 I will keep thinking about it and post back.....<o:p></o:p>

 Thanks<o:p></o:p>