Heat of Crystallization of Sodium Thiosulfate Pentahydrate
Name:
Date:
Data and Observations (@ 5 points)
Mass Na2S2O3 . 5 H2O
Volume Cold
Water Bath
g Initial Water Bath Temp. (t1)
o
mL Final Water Bath Temp. (t2)
o
Observations
in Step 6 – Drop in
Seed Crystal
Calculations (@ 10 points)
1. Calculate the heat
absorbed by the coldwater bath. Use the
calorimetry formula on
your reference sheets.
2. Calculate the heat of
crystallization. Divide
answer in #1 by the actual
mass used.
3. Calculate your absolute
error. Consult your
reference sheets for the
formula.
(200 J/g = theoretical)
4. Calculate your percent
error. Consult your
reference sheets for the
formula.
(200 J/g = theoretical)
SC6. Students will understand the effects motion of atoms and molecules in chemical and physical processes.
b. Collect data and calculate the amount of heat given off or taken in by chemical or physical processes.
c. Analyzing (both conceptually and quantitatively) flow of energy during change of state (phase).
 You exceeded the standard(s).
 You met the standard(s).
 You did not meet the standard(s)
C
C
Heat of Crystallization of Sodium Thiosulfate Pentahydrate
Name:
Date:
Respond in complete sentences. (@ 10 points)
1. In Step 7, what is the actual source of the heat energy released by the sodium thiosulfate
that was absorbed later by the cold-water bath?
2. How does the heats of crystallization and fusion for sodium thiosulfate compare? If
necessary, consult your textbook or a reference source.
3. This experiment could not be performed with a mixture of substances. Explain.
4. One real problem with solar heating is the difficulty in storing the sun’s heat during nighttime
hours. Describe how sodium thiosulfate pentahydrate could possibly be used to solve this
problem. (20 points)
SC6. Students will understand the effects motion of atoms and molecules in chemical and physical processes.
b. Collect data and calculate the amount of heat given off or taken in by chemical or physical processes.
c. Analyzing (both conceptually and quantitatively) flow of energy during change of state (phase).
 You exceeded the standard(s).
 You met the standard(s).
 You did not meet the standard(s)