Chemistry 2080
Spring 2009
Problem Set #2

due date: Friday February 6th at 2 pm
Name:__
_(Key)________
Lab TA Name:__________________ Lab Day/Time:______________________
Practice problems (not graded). Chapter 7:
24, 29, 33.
1)
Cayuga Lake has a surface area of about 172 km
2
and a volume of 9.4 km
3
.
When the sun is shining brightly
in the Summer, it is pouring about 200 watts per meter
2
onto the surface of the lake.
How many hours
of bright
sunshine would be needed to raise the temperature of the surface of the lake, down to a depth of 2 meters, by
10°C?
Assume that the energy of the sunshine is captured completely by the top 2 meters of the lake, that there is
no loss of heat to the environment during periods of no sunshine, and that the top 2 meters of the lake gets
magically stirred, without mixing with the water below.
[Note that 1 watt = 1 J/sec].
For this problem, we don’t need to know the area of the lake, we
can do the calculation on any one square meter. Each m
2
of the lake has associated with it a
volume of 2.0 m
3
.
This volume of water weighs 2 x 10
6
g.
200 watts = 200 J/sec, or (200 x 60 x 60) J/hour.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '07
 DAVIS,F
 Chemistry, Combustion, complete combustion, Cayuga Lake

Click to edit the document details