CHE1020
Spring 2009
Calorimetry Lab Write-up
TO: Joan Richmond, Chemistry Professor
FROM: Melissa Wood, Student
LAB PARTNER: Megan Miller
DATE: February 10, 2009
SUBJECT: Calorimeter Lab
Purpose: To design a closed system and see the heat absorbed by the water
given off by the NaOH pellets.
Summary: From this lab I learned that accuracy is extremely important
especially with calculations. My partner and I discovered that our temperature
readings were off by a decimal place which meant that all our calculations were
off.
Procedures: My partner and I started out by creating a table for all our data and
gathering our supplies. Then we weighed and recorded the weigh boat and tried
to weigh out two grams of NaOH pellets. After we recorded that data we used a
graduated cylinder to pour eighty milliliters of water into a small beaker and
recorded the volume. Next we used a thermometer to find and record the initial
temperature of the water. We then placed the beaker into our calorimeter and
added our NaOH pellets. A thermometer was sticking out of the lid to the
calorimeter and continually stirring the water and pellets we took a temperature
reading every fifteen seconds until we had six readings that were the same. We
then repeated this experiment two more times.
Data Table:
Weigh Boat (g)
Mass NaOH Pellets (g)
Volume of H2O (mL)
In. Temp (°C)
Final Temp (°C)
Trial 1
1.90
3.99
81.1
19.0
24.5
Trial 2
1.90
4.09
80.1
17.1
22.7
Trial 3
1.89
5.23
80.02
20.6
29.1
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CHE1020
Spring 2009
Results:
Calculations
∆T=Tf-Ti
Mass of H2O
∆H=(mass)(sh)( ∆T)
∆H=31.0J/°C) ( ∆T)
Convert J KJ for 3&4
Mole of NaOH
∆H in KJ per mole of NaOH
Trial 1
5.5°C
81.00g
1864J
170.5J
2.03KJ
.05mole
40.62 KJ/Mole
Trial 2
5.6°C
80.00g
1875J
173.6J
2.05KJ
.05mole
41.00KL/mole
Trial 3
8.5°C
79.92g
2843J
263.5J
3.11KJ
.08mole
38.8KJ/mole
Calculate Mean and SD of the change in heat (KJ/mole)
Mean = 40.14
Standard Deviation = 1.12
Commentary: Our results were not similar to other groups; our change in
temperature (initial to final) was much lower than most groups. This could be
caused by faulty equipment, i.e. our thermometer, or human error, us not
reading the thermometer correctly. Perhaps we didn’t measure out enough
NaOH pellets to cause a greater temperature change. Also the closed
environment of our calorimeter system could’ve caused the slow change in
temperature. Something to improve would be trying to develop a calorimeter
that allows less air in (not having the thermometer sticking out through the lid
of the calorimeter).
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