Anglia Ruskin University Find the Specific Heat of Water Chemistry Questions

UNIT IV STUDY GUIDEThermochemistry
Course Learning Outcomes for Unit IV
Upon completion of this unit, students should be able to:
2. Describe how chemistry is a science of exact measurement.
2.1 Relate mass, change in temperature, and specific heat (or heat capacities) to the energy
needed to complete a heat transfer process.
2.2 Distinguish between the system and surroundings in thermodynamics.
2.3 Identify the relationship between energy, work, and heat.
3. Explain the relationship between chemical matter and energy.
3.1 Apply Hess’s law to determine enthalpy change of a reaction.
Course/Unit
Learning Outcomes
2.1
2.2
2.3
3.1
Learning Activity
Unit Lesson
Chapter 5, pp. 163–201
Unit IV Quiz
Unit Lesson
Chapter 5, pp. 163–201
Unit IV Quiz
Unit Lesson
Chapter 5, pp. 163–201
Unit IV Quiz
Unit Lesson
Chapter 5, pp. 163–201
Unit IV Lab Assignment
Required Unit Resources
Chapter 5: Thermochemistry, pp. 163–201
Unit Lesson
Chapter 5
The Nature of Energy (5.1)
Thermodynamics is the study of energy and work transformations in systems. The study of the changes of
heat in chemical reactions is called thermochemistry.
There are two types of energy—potential energy and kinetic energy. Potential energy is stored energy. The
food we eat, a flashlight with batteries, and a car filled with gasoline all have potential energy. Kinetic energy
is energy of motion. A child running, a plane flying, and a lawn mower cutting grass all have kinetic energy.
The international system of units (SI) measurement of energy is the joule (J). Another common energy unit is
the calorie (cal). One calorie is the amount of heat needed to raise the temperature of 1 gram of water by 1
Celsius degree.
CHM 1301, General Chemistry I
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When we study thermodynamic properties, we define a specific amount of matter
asx the
system.
Everything
UNIT
STUDY
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outside the system is the surroundings. When we study a chemical reaction, the
system is the reactants and
Title
products. The type of system with which one is dealing can have important implications in chemistry because
each type of system dictates certain conditions and laws of thermodynamics that are associated with that
system. Energy can be transferred between the system and the surroundings as work or heat.
The First Law of Thermodynamics (5.2)
The internal energy in a chemical system is the sum of the potential and kinetic energies of the atoms,
molecules, or ions in the system. The internal energy of a system can change because of energy transferred
between the system and the surroundings. According to the first law of thermodynamics, the energy change
for a system (U) is the sum of the energy transferred as heat between the system and its surroundings (q)
and the energy transferred as work between the system and its surroundings (w).
In an endothermic process, the system absorbs heat from the surroundings; in an exothermic process, the
system releases heat to the surroundings. Reactions that release heat to the surroundings are called
exothermic reactions. Reactions that absorb heat are called endothermic reactions.
Enthalpy and Calorimetry (5.3 & 5.5)
When a gas is produced or consumed in a chemical reaction occurring at constant pressure, the system may
perform pressure-volume (P-V) work against the prevailing pressure of the surroundings. For this reason, we
define a new state function called enthalpy, H, which is related to energy.
The enthalpy change for a chemical reaction is equal to the heat absorbed or gained during the reaction. The
enthalpy change for a reaction is written as the enthalpy of the products minus the enthalpy of the reactants.
Enthalpy changes are represented by the symbol ∆H, which is read delta H.
Calorimetry is the study of heat flow and heat measurement. Calorimetry experiments determine the heat
(enthalpy changes) of reactions by making accurate measurements of temperature changes produced in
a calorimeter.
The temperature change of a calorimeter depends on its heat capacity. The heat capacity of an object is the
amount of heat needed to raise the temperature of the object by 1 Celsius degree. The heat capacity for one
mole of a pure substance is called its molar heat capacity; for one gram of the substance, we use the term
specific heat. The specific heat of liquid water is 4.184 J/g Co. To raise the temperature of 1 gram of H2O (l)
by 1 Celsius degree, 4.184 joules of heat must be added.
If a calorimetry experiment is carried out under a constant pressure, the heat transferred provides a direct
measure of the enthalpy change of the reaction. A bomb calorimeter has a fixed volume. It consists of a wellinsulated container filled with a known mass of water, in which the reaction of interest is carried out.
A coffee-cup calorimeter is a simple instrument that can be
used to measure temperature changes of reactions at
constant pressure. Do you know why two Styrofoam® cups
are used instead of just one?
(Brown et al., 2018, p. 180)
CHM 1301, General Chemistry I
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Hess’s Law and Enthalpies of Formation (5.6 & 5.7)
UNIT x STUDY GUIDE
Title
Hess’s law states that if a series of reactions are added together, the enthalpy change for the net reaction will
be the sum of the enthalpy changes for the individual steps.
Enthalpy depends only on the initial and final states of the system. Thus, the enthalpy change of a process is
the same whether the process is carried out in one step or in a series of steps.
The enthalpy of formation of a substance is the enthalpy change for the reaction in which the substance is
formed. The standard molar enthalpy of formation is the enthalpy change for the formation of 1 mol of a
compound directly from its component elements in their standard states. The standard enthalpy change for
any reaction can be readily calculated from the standard enthalpies of formation of the reactants and products
in the reaction.
Enthalpy diagram for combustion of 1
mol of methane
(Brown et al., 2018, p. 186)
Foods and Fuels (5.9)
The fuel value of a substance is the heat released when one gram of the substance is combusted. Fuels are
chemical compounds that burn readily with the release of large amounts of energy. The foods you eat are
your body’s fuel. They react to provide the energy required for all your body’s activities.
The most common nonfood fuels are hydrocarbons. Hydrocarbons are found as fossil fuels such as natural
gas, petroleum, and coal, with coal as the most abundant. Renewable energy sources include solar energy,
wind energy, biomass, and hydroelectric energy. Nuclear power does not utilize fossil fuels but does create
controversial waste-disposal problems.
Reference
Brown, T. L., LeMay, H. E., Jr., Bursten, B. E., Murphy, C. J., Woodward, P. M., & Stoltzfus, M. W. (with
Lufaso, M. W.). (2018). Chemistry: The central science (14th ed.). Pearson.
CHM 1301, General Chemistry I
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Suggested Unit Resources
UNIT x STUDY GUIDE
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In order to access the following resources, click the links below.
ChemGuy on YouTube further explains some of the more challenging concepts/problems from Chapter 5.
This video discusses energy laws.
1chemguy. (2010, March 16). Chemguy chemistry W3D7V6 [Video].

Transcript for Chemguy Chemistry W3D7V6 video
This video discusses calculating q.
1chemguy. (2010, March 16). Chemguy chemistry X3R6Y2 [Video]. https://www.youtube.com/watch?v=44ulKzpTeQ
Transcript for Chemguy Chemistry X3R6Y2 video
This video discusses calorimetry.
1chemguy. (2010, March 15). Chemguy chemistry S9Y4D8 [Video].

Transcript for Chemguy Chemistry S9Y4D8 video
This video discusses heat of formation and stoichiometry.
1chemguy. (2010, March 12). Chemguy chemistry J4E7T4 [Video]. https://www.youtube.com/watch?v=jLIyvyu4hg
Transcript for Chemguy Chemistry J4E7T4 video
This video discusses Hess’s law
1chemguy. (2010, March 11). Chemguy chemistry C3T7R8 [Video].

Transcript for Chemguy Chemistry C3T7R8 video
Learning Activities (Nongraded)
Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit
them. If you have questions, contact your instructor for further guidance and information.
To help you better prepare for the unit quiz and final exam, it is highly recommended that you complete the
Unit IV Practice Problems Worksheet. The worksheet includes an answer table.
For additional help, the video on Unit IV Worked Problems is available.
Transcript for Unit IV Worked Problems video
Before attempting the homework assignment, you are encouraged to view the Unit IV Handout for additional
help. The knowledge checks in the handout are designed to provide practice on math-heavy portions of your
quizzes and homework assignments.
CHM 1301, General Chemistry I
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As you complete the required reading for this unit in the textbook, consider taking
additional
time to
UNITthe
x STUDY
GUIDE
work the sample exercises to make sure you understand all the concepts and Title
actions that were covered in
that section.
Additional practice that will help you master the chapter’s educational content is provided in the exercises on
pp. 202–211 (Chapter 5). Answers to the odd-numbered exercises are provided in the back of the textbook.
If there is anything you do not understand or an exercise you are unable to successfully complete, contact
your instructor for additional explanation or information.
CHM 1301, General Chemistry I
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