Solutions to Homework #2 (Astronomy 155). 5 points each part, total 40.
1. I took this problem straight off the website for chemistry that I had a link to, on the
course webpage.
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/rateframe.html
and follow links to chemical kinetics, and activation energy.
This is problem #1112.
The answer was 183 kJ/mole for the first part, and 1.6 M/sec for the second part.
Depending on how you did the second part, you may have gotten 2.0 M/sec, because the
data points did not make a perfectly straight line.
I did not take points off if you did a good job of handwriting your plots, but most people
did not do such a great job of that, so I dinged you a few points! Yikes  isn’t it easier to
do it on excel?
2. You can safely assume that the ice+water mixture starts at 0
o
C. The specific heat of
water c = 4.19 kJ/kgK. latent heat of fusion L
f
= 335 kJ/kg, and latent heat of
vaporization L
vap
= 2270 kJ/kg. Here are the terms that go into determining the energy to
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This note was uploaded on 09/08/2010 for the course ASTR 155 at San Jose State.
 '10
 Kress,Monika
 Astronomy

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