PASCO Specialty & Mfg. ME-8569 User Manual Page 16

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scientific
12
012-04774A
3. Watch the temperature of the cold water rise, stirring the
water gently. After several minutes, the temperature will
peak out (above room temperature) and began to fall.
Record this equilibrium (peak) temperature to the nearest
tenth of a degree in Table 1.
4. After the equilibrium temperature has been reached,
remove the object from the water and weigh the water with
the cup. Subtract the mass of the cup from the mass of the
water with the cup and record the mass of the water in
Table 4.1.
5. Calculate the change in temperature for the object:
T = HOT TEMP - EQUILIBRIUM TEMP.
Record this in Table 4.2.
6. Calculate the change in temperature for the water in the
styrofoam cup:
T = EQUILIBRIUM TEMP - COLD TEMP.
Record this in Table 4.2.
7. When the object is cooled in the water, the heat lost by
the object is equal to the heat gained by the water because
energy is conserved (neglecting any losses to the environ-
ment):
Q
OBJECT
= Q
WATER
(mcT)
OBJECT
= (mcT)
WATER
Solving for the specific heat of the object gives:
c =
where c
WATER
is 1 cal/g °C. Calculate the specific heat for
the object and record the results in Table 4.2.
8. Look up the accepted value for the specific heat for the
material used and record in Table 4.2. Calculate the percent
difference between the experimental value and the accepted
value.
9. Repeat this procedure for the other objects.
QUESTIONS
1. Do the two aluminum objects have the same specific
heat?
2. Do the two brass objects have the same specific heat?
3. How does starting the cold water below room temperature
minimize the effect of the losses to the environment?
OBJECT OBJECT T WATER T
SPECIFIC
HEAT
ACCEPTED
VALUE
%
DIFF.
AL. CYL.
AL. BLOCK
BRASS CYL.
BRASS BLOCK
Table 4.2: Calculations
Figure 2: Equilibrium Temperature
m
WATER
c
WATER
(T)
WATER
m
OBJECT
(T)
OBJECT
Thermometer
Submerge mass
in water
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