Heat Math Worksheet (First Exposure)
Gas
Q = m DH
DHcond
-DHvap
DHvap
Liquid
DHfus
NOTE: Figure 17.9 on page 520 is in error.
It says “-DHcond and –DHsolid,” but it the minus signs don’t
belong there. Either that or I’m a monkey’s uncle.
-DHfus
DHsolid
Solid
Init 4/10/2014 by Daniel R. Barnes
C=?
Q=?
T=?
m=?
(Solving for T)
. . . solve q = m DT Cp problems
17. A corn cob is heated up in boiling water to a temperature
of 100 oC. The corn cob has a mass of 400 g and absorbed
16,000 cal of heat from the boiling water. What was the
original temperature of the corn cob? Assume that the
specific heat of the corn cob is 1 cal/goC.
Tf = 100 oC
m = 400 g
Cp = 1 cal/goC
DT = Tf – Ti = ?
q = m DT Cp
m Cp
m Cp
DT =
q = 16,000 cal
Ti = ? oC
Ti = Tf – DT
q = m DT Cp
16,000 cal
= 40 oC = DT
(400 g)(1 cal/goC)
Ti = Tf – DT = 100 oC – 40 oC = 60 oC = Ti
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