BAGUIO COLLEGE OF TECHNOLOGY
# 37 Harrison Road/51 Plaza Natalia Naguilian Road
Baguio City
Tel. Nos: 442-3743 / 424-0859
SUBJECT TITLE
: CHEMISTRY FOR ENGINEERS
NOMINAL DURATION
: 50 HOURS (Laboratory)
COURSE DESCRIPTION
: This course provides students with core concepts
of Chemistry that are important in the practice of
Engineering profession.
BAGUIO COLLEGE OF TECHNOLOGY
Baguio City, Philippines
MODULE TITLE
: Calorimetry
MODULE NO
:1
NOMINAL DURATION
: 5 Hours – August 24 – 29, 2020
LEARNING OBJECTIVES: At the end of this module, the students should be able to:
a. explain the concept and technique of calorimetry;
b. calculate related properties using typical calorimetry data; and
c. describe a simple calorimeter and how does it function.
MODULE CONTENT:
Calorimetry
 is the process of measuring the amount of heat released or absorbed during a chemical reaction.
 By knowing the change in heat, it can be determined whether or not a reaction is exothermic
(releases heat) or endothermic (absorbs heat).
 Calorimetry is frequently performed in order to determine the heat of reaction or the heat of
fusion or the heat of dissolution or even the specific heat capacity of a metal.
 Calorimetry also plays a large part of everyday life, controlling the metabolic rates in humans and
consequently maintaining such functions like body temperature.
 In humans, metabolism is typically measured in Calories per day. A nutritional calorie (Calorie) is
the energy unit used to quantify the amount of energy derived from the metabolism of foods;
one Calorie is equal to 1000 calories (1 kcal), the amount of energy needed to heat 1 kg of water
by 1 °C.
Calorimeters
 A calorimeter is a device used to measure the quantity of heat transferred to or from an object.
 It is a coffee cup (Styrofoam cup) calorimeter - usually filled with water. The more sophisticated
cases include a lid on the cup with an inserted thermometer and maybe even a stirrer.
A calorimeter laboratory set-up
 The assumption behind the science of calorimetry is that the energy gained or lost by the water
is equal to the energy lost or gained by the object under study.
BCT LEARNING MODULE 2020-2021
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BAGUIO COLLEGE OF TECHNOLOGY
Baguio City, Philippines
 If an attempt to determine the specific heat of fusion of ice using a coffee cup calorimeter, then
the assumption is that the energy gained by the ice when melting is equal to the energy lost by
the surrounding water.
 It is assumed that there is a heat exchange between the ice and the water in the cup and that no
other objects are involved in the heat exchanged.
 The quantity of energy gained or lost is given by the equation, Q = mwater•Cwater•ΔTwater ;
Where Cwater is 4.18 J/g/°C. So if the mass of water and the temperature change of the water
in the coffee cup calorimeter can be measured, the quantity of energy gained or lost by the
water can be calculated.
 The Styrofoam in a coffee cup calorimeter reduces the amount of heat exchange between the
water in the coffee cup and the surrounding air.
 The value of a lid on the coffee cup is that it also reduces the amount of heat exchange between
the water and the surrounding air. The more that these other heat exchanges are reduced, the
more true that the above mathematical equation will be.
 Any error analysis of a calorimetry experiment must take into consideration the flow of heat from
system to calorimeter to other parts of the surroundings. And any design of a calorimeter
experiment must give attention to reducing the exchanges of heat between the calorimeter
contents and the surroundings.
Bomb Calorimetry
 A cheap Styrofoam cup and a thermometer is not appropriate for a commercial food
manufacturer to determine the Calorie content of their products.
 Chemists often use a device known as a bomb calorimeter to measure the heat exchanges
associated with chemical reactions, especially combustion reactions.
 Having little to nothing to do with bombs of the military variety, a bomb calorimeter includes a
reaction chamber where the reaction (usually a combustion reaction) takes place. The reaction
chamber is a strong vessel that can withstand the intense pressure of heated gases with
exploding.
 The caloric content of foods can be determined by using bomb calorimetry; that is, by burning the
food and measuring the energy it contains. A sample of food is weighed, mixed in a blender,
freeze-dried, ground into powder, and formed into a pellet. The pellet is burned inside a bomb
calorimeter, and the measured temperature change is converted into energy per gram of food.
 The chamber is typically filled with mostly oxygen gas and the fuel. An electrical circuit is wired
into the chamber in order to electrically ignite the contents in order to perform a study of the
heat released upon combustion. The reaction chamber is surrounded by a jacket of water with a
thermometer inserted.
 The heat released from the chamber warms the water-filled jacket, allowing a scientist to
determine the quantity of energy released by the reaction.
BCT LEARNING MODULE 2020-2021
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BAGUIO COLLEGE OF TECHNOLOGY
Baguio City, Philippines
 Today, the caloric content on food labels is derived using a method called the Atwater system that
uses the average caloric content of the different chemical constituents of food, protein,
carbohydrate, and fats.
 The average amounts are those given in the equation and are derived from the various results
given by bomb calorimetry of whole foods. The carbohydrate amount is discounted a certain
amount for the fiber content, which is indigestible carbohydrate. To determine the energy
content of a food, the quantities of carbohydrate, protein, and fat are each multiplied by the
average Calories per gram for each and the products summed to obtain the total energy.
Constant Pressure Calorimetry


In order to measure the heat of a reaction, the reaction must be isolated so that no heat is lost to
the environment. This is achieved by use of a calorimeter, which insulates the reaction to better
contain heat.
Coffee cups are often used as a quick and easy to make calorimeter for constant pressure. More
sophisticated bomb calorimeters are built for use at constant volumes.
Constant Volume Calorimetry
 Constant Volume (bomb) calorimetry, is used to measure the heat of a reaction while holding
volume constant and resisting large amounts of pressure.
 Although these two aspects of bomb calorimetry make for accurate results, they also contribute
to the difficulty of bomb calorimetry.
 Here, the basic assembly of a bomb calorimeter will be addressed, as well as how bomb
calorimetry relates to the heat of reaction and heat capacity and the calculations involved in
regards to these two topics.
Differential Scanning Calorimetry
 Differential scanning calorimetry is a specific type of calorimetry including both a sample
substance and a reference substance, residing in separate chambers.
 While the reference chamber contains only a solvent, the sample chamber contains an equal
amount of the same solvent in addition to the substance of interest, of which the ΔH is being
determined.
 The ΔH due to the solvent is constant in both chambers, so any difference can be attributed to
the presence of the substance of interest.
BCT LEARNING MODULE 2020-2021
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BAGUIO COLLEGE OF TECHNOLOGY
Baguio City, Philippines
Determining the Heat of Reaction
The amount of heat that the system gives up to its surroundings so that it can return to its initial
temperature is the heat of reaction. The heat of reaction is just the negative of the thermal energy
gained by the calorimeter and its contents (qcalorimeter ) through the combustion reaction.
Formulas:
(equation 1)
ΔH = qV +ΔngRT
(where Δng, change of moles in gas reaction)
If the constant volume calorimeter is set up the same way as before, (same steel bomb, same
amount of water, etc.) then the heat capacity of the calorimeter can be measured using the following
formula:
(equation 2)
qrxn = −qcalorimeter
(equation 3)
qcalorimeter = qbomb +qwater
(equation 4)
qcalorimeter = (heat capacity of calorimeter)×ΔT
Calorimetry Problem Solving Example
Maria Claro was assigned to determine the experimental value for the heat of fusion of ice. She
dry and mass out 36.9 gram of ice and place it into a coffee cup with 80 g of water at 45.6°C. She placed
a lid on the coffee cup and insert a thermometer. After several minutes, the ice has completely melted
and the water temperature has lowered to 12.3°C. What is her experimental value for the specific heat of
fusion of ice?
The basis for the solution to this problem is the recognition that the quantity of energy lost by the
water when cooling is equal to the quantity of energy required to melt the ice. In equation form, this could
be stated as
Qice = -Qcalorimeter
(The negative sign indicates that the ice is gaining energy and the water in the calorimeter is losing
energy.) Here the calorimeter (as in the Qcalorimeter term) is considered to be the water in the coffee cup.
Since the mass of this water and its temperature change are known, the value of Qcalorimeter can be
determined.
Solution:
Qcalorimeter = m•C•ΔT
Qcalorimeter = (80 g)•(4.18 J/g/°C)•(12.3°C - 45.6°C)
Qcalorimeter = -11,1135.52 J
The negative sign indicates that the water lost energy. The assumption is that this energy lost by
the water is equal to the quantity of energy gained by the ice. So Qice = +11,1135.52 J. (The positive sign
indicates an energy gain.) This value can be used with the equation from the previous page to determine
the heat of fusion of the ice.
Qice = mice•ΔHfusion-ice
+11,1135.52 J = (36.9 g)•ΔHfusion-ice
ΔHfusion-ice = (+11,1135.52 J)/(36.9 g)
ΔHfusion-ice = 3,011.80 J/g
BCT LEARNING MODULE 2020-2021
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BAGUIO COLLEGE OF TECHNOLOGY
Baguio City, Philippines
EVALUATION/ASSESSMENT/PERFORMANCE TASK:
NAME:_________________________________
STRAND & YEAR: ________________________
DATE ACCOMPLISHED:____________________
SCORE:
NOTE: Please submit this part on or before AUGUST 29, 2020.
I. MATCHING TYPE. Match the definitions/descriptions on column A to its’ corresponding term/concept
on column B. Write the letter of the correct answer before each test item.
A
______1. Used to determine the caloric content of
food products
______2. A type of calorimetry that uses a reference
substance and a sample substance
______3. A device used to measure the heat
transferred to or from an object
______4. A process used to determine the heat
absorbed or released in a chemical reaction
______5. A type of calorimetry that usually uses
Styrofoam cup to contain the heat better
______6. A product of a bomb calorimetry which is
burned to determine the energy per gram contained
in a food product
______7. A chemical reaction that absorbs heat, and
decreases the temperature of the solution
______8. The formula used to measure the quantity
of energy lost or gained in a reaction/solution
______9. An instrument used in a calorimeter that
measures the temperature of the liquid in the inner
vessel of a calorimeter.
______10. A chemical reaction that releases heat,
thereby increases the temperature of the solution
B
A. constant pressure calorimetry
B. calorimetry
C. calorimeter
D. differential scanning calorimetry
E. bomb calorimetry
F. pellet
G. endothermic
H. Q = mwater x Cwater x ΔTwater
I. thermometer
J. exothermic
K. ΔH = qV +ΔngRT
ASSIGNMENT: Do an advance reading on the next topic, Heat of Combustion.
REFERENCES:





Brown, Lawrence and Holme, Thomas A. (2011). Chemistry for Engineering Students. Second
Edition. Belmont, CA: Brooks, Cole/Cengage Learning.
Libretexts
Org.
(Aug
16,
2020).
Calorimetry.
Retrieved
from
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/
Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/Calorimetry
Calorimeters
and
Calorimetry.
Retrieved
from
https://www.physicsclassroom.com/class/thermalP/Lesson-2/Calorimeters-and-Calorimetry
Electrochemical
energy.
Retrieved
from
https://courses.lumenlearning.com/chemistryformajors/chapter/calorimetry/
Differential
Scanning
Calorimetry
(DSC).
Retrieved
from
https://www.skz.de/en/research/technicalfacilities/pruefverfahrenl/thermischeeigenshaftenl/4856.Differential-Scanning-Calorimetry.html
Prepared by:
MS. SAMANTHA M. QUIAMBAO
BCT LEARNING MODULE 2020-2021
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