PASCO ET-8499 Energy Transfer Calorimeter - Manual (Page 13)

Model No. ET-8499 Experiment 2: Entropy
11 ®
Experiment 2: Entropy
Purpose
This lab investigates the concept of entropy as applied to calorimetry. The relationship between
entropy and spontaneous processes is investigated.
Theory
In a closed system, heat energy flows spontaneously from the hot objects to the cooler objects and
the total change in energy for the system is zero. The heat added to one part of the system equals
the heat lost by the other parts. However, the total change in entropy of the system is not zero. For
any real, spontaneous process, the total change in entropy of the entire system must be greater
than zero.
The change in entropy (
∆
S) of an object is defined in terms of the energy transferred (dQ) and the
temperature of the object (T).
For a calorimetry experiment, dQ=mcdT , where
m = mass
c = specific heat
Thus, equation (1) can be reduced to
Equipment Required
Calorimeter
(2) Thermometer or Temperature sensor (0.1° resolution)
Water (hot and cold)
Scale
S
∆
S
f
S
i
dQ
T
------- (1)
i
f
∫
= – =
S
∆
mc
dT
T
------ (2)
i
f
∫
=