Calorimetry is the scientific study of heat transfer during chemical reactions, explored in this lab report. The experiment utilizes a Styrofoam calorimeter to measure heat evolved or absorbed from various reactions, including acid-base neutralizations and metal reactions. Key equations such as Qrxn = mCΔT and ΔH = Qrxn/n are applied to calculate enthalpy changes. This report is designed for chemistry students conducting calorimetry experiments and provides insights into error analysis and theoretical versus experimental heat comparisons. It includes detailed methodologies and results for multiple chemical reactions.

Key Points

  • Explores calorimetry principles using a Styrofoam calorimeter for heat measurement.
  • Applies key equations like Qrxn = mCΔT for calculating heat of reactions.
  • Analyzes various chemical reactions, including acid-base and metal reactions.
  • Discusses error sources affecting calorimetry results and their implications.
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UNIVERSITY OF THE PHILIPPINES
Diliman, Quezon City
Calorimetry
SUBMITTED BY: Frances Abegail G. Quezon SECTION: WFW/WFQR2
SUBMITTED TO: Ms. Irina Diane Castanos DATE: November 21, 2012
INTRODUCTION
Calorimetry is the measurement of heat evolved or absorbed from a reaction. It is
derived from the Latin word, calor, meaning heat and the Greek word metry, meaning to
measure.
The process of calorimetry makes use of a device called a calorimeter. The
calorimeter measures the heat of reaction of the system. The heat of reaction is the heat
required for the system to return to its original state.
The experiment makes use of a Styrofoam ball that acts as the calorimeter. It acts
in the same principle as the coffee-cup calorimeter. The first part of the experiment is
calibration of the calorimeter where the heat capacity of the calorimeter would be
determined for further use.
The equations used for the experiment are the following:
Qrxn = mCΔT
Qrxn = -Qcal
Qcal = CcalΔT
ΔH = Qrxn /n
ΔH = enthalpy of formation of products – enthalpy of formation of reactants
Where: Qrxn = heat of reaction
m = mass
ΔT = temperature change
Qcal = heat of calorimeter
Ccal = heat capacity of calorimeter
ΔH = enthalpy of reaction
For the computation of the theoretical enthalpy of reaction, a table of standard
heats of formation for some substances is used.
Substance heat of formation(kJ/mol)
Ca
2+
(aq)
-542.83
Mg
2+
(aq)
-466.85
Zn
2+
(aq)
-153.89
CO
3
2-
(aq)
-677.14
OAc
-
(aq)
-486.01
NH
4
+
(aq)
-132.51
NH
3
(aq)
-80.29
Cu
2+
(aq)
+64.77
Al
3+
(aq)
-677.14
H
+
(aq)
0.00
CaCO
3
(s)
-1206.9
CH
3
COOH
(aq)
-485.76
H
2
O
(l)
-285.83
OH
-
(aq)
-229.99
The following chemical reactions are witnessed in the experiment in the same
order as below:
NH
3
(aq)
+ H
+
(aq)
NH
4
+
(aq)
CH
3
COOH
(aq)
+ OH
-
(aq)
OAc
-
(aq)
+ H
2
O
(l)
NH
3
(aq)
+ CH
3
COOH
(aq)
NH
4
+
(aq)
+ OAc
-
(aq)
H
+
(aq)
+ OH
-
(aq)
H
2
O
(l)
2 H
+
(aq)
+ Mg
(s)
Mg
2+
(aq)
+ H
2(g)
Mg
(s)
+ 2 CH
3
COOH
(aq)
Mg
2+
(aq)
+ 2OAc
-
(aq)
+ H
2(g)
Cu
2+
(aq)
+ Zn
(s)
Zn
2+
(aq)
+ Cu
(s)
Ca
2+
(aq)
+ CO
3
2-
(aq)
CaCO
3
(s)
The purpose of this experiment is to determine the heat evolved or absorbed from
the given reaction and compare it to the theoretical. It is also done to practice the students
in the process of calorimetry.
ANSWERS TO QUESTIONS
From Manual:
1. Errors could arise from the improper set-up of the calorimeter. The Styrofoam ball
could be damaged which could cause improper insulation, therefore, improper
temperature readings. Wrong preparation of solutions would also cause discrepancies
from the experimental and theoretical heat of reaction. Using a wet test tube would also
yield incorrect results because it would lead to the misreading of the temperature.
Residue from chemicals used in the calibration or previous trials that are left from
improper washing would also affect experimental results.
2. a.) Because of the set-up used. We used an 8” or larger Styrofoam ball and a 6” test
tube. A lesser amount of solution might cause the improper reading of the temperature
because the bulb would not reach the solution. A big difference from 15ml might fill the
test tube and interfere with proper temperature readings.
b.) We need to know the concentration of reactants in order to solve for their moles and
further for the limiting reagent in the reaction. The moles of limiting reagent would then
be used to compute for the enthalpy of reaction.
c.) For the same reason of knowing the concentration of liquid reactants, knowing the
weight of metals would let us know the number of moles that we would use in the
reaction. Using stoichiometry, we could compute for the moles of the limiting reagent
which we could use for computing the enthalpy of reaction.
3. a.) mol = 0.2 L (0.5 M) = 0.1 moles HA
Enthalpy = -6 kJ/0.1 moles = -60 kJ/mol
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End of Document
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FAQs

What is the purpose of the calorimetry experiment?
The purpose of the calorimetry experiment is to measure the heat evolved or absorbed during chemical reactions and compare these values to theoretical predictions. By using a Styrofoam calorimeter, students can accurately gauge temperature changes in reactions such as acid-base neutralizations and metal displacements. This hands-on approach helps students understand the principles of thermodynamics and the concept of enthalpy in chemical processes.
What equations are used in the calorimetry lab report?
Key equations used in the calorimetry lab report include Qrxn = mCΔT, which calculates the heat of the reaction based on mass, specific heat capacity, and temperature change. Additionally, Qrxn = -Qcal relates the heat of the reaction to the heat absorbed by the calorimeter, while ΔH = Qrxn/n provides the enthalpy change per mole of reactants. These equations are essential for analyzing the thermodynamic properties of the reactions studied.
What types of reactions are analyzed in the calorimetry experiment?
The calorimetry experiment analyzes several types of reactions, including acid-base neutralizations and metal reactions. Specific reactions include the neutralization of ammonia with hydrogen ions, the reaction of magnesium with acetic acid, and the displacement reaction between copper ions and zinc metal. Each reaction's heat transfer is measured to determine the enthalpy changes, providing insights into their thermodynamic behavior.

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