PORTAGE CHEMISTRY 103 MODULE 3 EXAM STUDY QUESTIONS
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
3.1: THERMOCHEMISTRY - CORRECT ANSWERS Thermodynamics is the study of the relationship
between heat and other forms of energy, particularly mechanical work. Thermochemistry is the part
of thermodynamics that deals with the quantity of heat given off or absorbed during a chemical
reaction. The quantity of heat given off or absorbed during a physical change or temperature change
can also be studied, and we will refer to this process as calorimetry.
System - CORRECT ANSWERS the object (or substance) being studied
Open system - CORRECT ANSWERS a system that permits the transfer of mass and energy with the
surroundings
Closed system - CORRECT ANSWERS a system that permits the transfer of energy but not mass with
the surroundings
Isolated system - CORRECT ANSWERS a system that does not permit the transfer of energy or mass
with the surroundings
Surroundings - CORRECT ANSWERS the rest of the universe interacting with the system
Energy - CORRECT ANSWERS the potential or capacity to move matter: the ability to do work (unit is
J = joule)
Work - CORRECT ANSWERS the amount of energy transferred by a force acting through a distance
Kinetic energy - CORRECT ANSWERS the energy possessed by an object by virtue of its motion (unit
is J = joule)
Potential energy - CORRECT ANSWERS the energy possessed by an object by virtue of its position
(unit is J = joule)
Heat (q) - CORRECT ANSWERS the thermal energy transferred between system and surroundings due
to a difference in temperature between them (unit is J = joule)
,PORTAGE CHEMISTRY 103 MODULE 3 EXAM STUDY QUESTIONS
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
Enthalpy - CORRECT ANSWERS the total energy of a system
Heat of reaction - CORRECT ANSWERS (ΔH) the amount of heat (q) gained or lost during a chemical
reaction
Exothermic - CORRECT ANSWERS a reaction with a - ΔH
Endothermic - CORRECT ANSWERS a reaction with a + ΔH (absorb heat)
Calorimetry - CORRECT ANSWERS The energy change that accompanies a physical, temperature, or
chemical change is determined by carrying out the process in a device known as a calorimeter. The
calorimeter is able to measure the amount of heat absorbed or evolved as a process takes place. A
styrofoam coffee cup calorimeter can be used to measure an energy change that takes place at
constant pressure. An enclosed bomb calorimeter is used to measure an energy change that takes
place at constant volume with a change in pressure.
Temperature change calorimetry - CORRECT ANSWERS measures the thermal energy change
occurring as a system at higher temperature transfers kinetic energy to a system at lower
temperature, which is reflected by a change in temperature for the overall system. This is
demonstrated below by adding a 15.6 gram piece of aluminum (heated to 100oC) to a 45.6 gram
sample of water at 26.7oC in a coffee cup calorimeter. The final temperature of this system can be
predicted using the equations below and several facts about the materials (Al and H2O).
Heat temp change = qtemp change = mass x specific heat (heat capacity) x temp change = m x c x ∆t
(mAl x cAl x ∆tAl) = (mH2O x cH2O x ∆tH2O)
However, since the Al is losing heat, we'll use a negative sign in front of the heat loss equation.
- (mAl x cAl x ∆tAl) = (mH2O x cH2O x ∆tH2O)
We know ∆t = Tempmixture - Tempinitial, so we can substitute the data to get:
- [15.6 g x 0.899 J/g oC x (Tmix - 100oC)] = [(45.6 g x 4.184 J/g oC x (Tmix - 26.70oC)]
, PORTAGE CHEMISTRY 103 MODULE 3 EXAM STUDY QUESTIONS
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
Now, solve:
- [14.0244 J/oC x (Tmix - 100oC)] = [(190.7904 J/oC x (Tmix - 26.7oC)]
- 14.0244 Tmix + 1402.44 = 190.79 Tmix - 5094.1
6496.44 = 204.8144 Tmix
Tmix = 6496..8144 = 31.7oC
Phase change calorimetry - CORRECT ANSWERS measures the energy change occurring as a
substance changes from one phase (state) to another, such as water melting or boiling, or ice
freezing or steam condensing. In this case, no temperature change occurs, but the energy change
causes the particles of the substance to form or break intermolecular bonds and change from one
state to another. The equations used to do phase change calorimetry calculations are shown below:
Phase changes of solid to liquid or liquid to solid:
qs↔i = mass x Heat of Fusion = m x ∆Hfusion
Phase Changes of liquid to gas or gas to liquid:
ql↔g = mass x Heat of Vaporization = m x ∆Hvapor
What is the energy involved in vaporization of 200 grams of water at 100oC if the heat of
vaporization for water is 2.26 kJ/g? - CORRECT ANSWERS When energy is given off in any of these
phase changes, a negative sign is placed in front of the value, and when energy is added, a positive
sign is placed in front of the value.
ql↔g = m x ∆Hvapor = 200 g x 2.26 kJ/g = 452 kJ (since heat is added) = + 452 kJ
What is the energy involved in freezing 200 grams of water at 0oC if the heat of fusion for water is
0.334 kJ/g? - CORRECT ANSWERS ql↔s = m x ∆Hfusion = 200 g x 0.334 kJ/g = 66.8 kJ (since heat is
removed/given off) = - 66.8 kJ
How much heat is involved to convert of 20 grams of ice at -10oC to 20 grams of steam at 120 oC? -
CORRECT ANSWERS ∆Hfusion = 0.334 kJ/g (H2O(l) ↔ H2O(s))
∆Hvapor = 2.26 kJ/g (H2O(l) ↔ H2O(g))
c (water) = 4.184 J/g oC
c (ice) = 2.09 J/g oC
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
3.1: THERMOCHEMISTRY - CORRECT ANSWERS Thermodynamics is the study of the relationship
between heat and other forms of energy, particularly mechanical work. Thermochemistry is the part
of thermodynamics that deals with the quantity of heat given off or absorbed during a chemical
reaction. The quantity of heat given off or absorbed during a physical change or temperature change
can also be studied, and we will refer to this process as calorimetry.
System - CORRECT ANSWERS the object (or substance) being studied
Open system - CORRECT ANSWERS a system that permits the transfer of mass and energy with the
surroundings
Closed system - CORRECT ANSWERS a system that permits the transfer of energy but not mass with
the surroundings
Isolated system - CORRECT ANSWERS a system that does not permit the transfer of energy or mass
with the surroundings
Surroundings - CORRECT ANSWERS the rest of the universe interacting with the system
Energy - CORRECT ANSWERS the potential or capacity to move matter: the ability to do work (unit is
J = joule)
Work - CORRECT ANSWERS the amount of energy transferred by a force acting through a distance
Kinetic energy - CORRECT ANSWERS the energy possessed by an object by virtue of its motion (unit
is J = joule)
Potential energy - CORRECT ANSWERS the energy possessed by an object by virtue of its position
(unit is J = joule)
Heat (q) - CORRECT ANSWERS the thermal energy transferred between system and surroundings due
to a difference in temperature between them (unit is J = joule)
,PORTAGE CHEMISTRY 103 MODULE 3 EXAM STUDY QUESTIONS
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
Enthalpy - CORRECT ANSWERS the total energy of a system
Heat of reaction - CORRECT ANSWERS (ΔH) the amount of heat (q) gained or lost during a chemical
reaction
Exothermic - CORRECT ANSWERS a reaction with a - ΔH
Endothermic - CORRECT ANSWERS a reaction with a + ΔH (absorb heat)
Calorimetry - CORRECT ANSWERS The energy change that accompanies a physical, temperature, or
chemical change is determined by carrying out the process in a device known as a calorimeter. The
calorimeter is able to measure the amount of heat absorbed or evolved as a process takes place. A
styrofoam coffee cup calorimeter can be used to measure an energy change that takes place at
constant pressure. An enclosed bomb calorimeter is used to measure an energy change that takes
place at constant volume with a change in pressure.
Temperature change calorimetry - CORRECT ANSWERS measures the thermal energy change
occurring as a system at higher temperature transfers kinetic energy to a system at lower
temperature, which is reflected by a change in temperature for the overall system. This is
demonstrated below by adding a 15.6 gram piece of aluminum (heated to 100oC) to a 45.6 gram
sample of water at 26.7oC in a coffee cup calorimeter. The final temperature of this system can be
predicted using the equations below and several facts about the materials (Al and H2O).
Heat temp change = qtemp change = mass x specific heat (heat capacity) x temp change = m x c x ∆t
(mAl x cAl x ∆tAl) = (mH2O x cH2O x ∆tH2O)
However, since the Al is losing heat, we'll use a negative sign in front of the heat loss equation.
- (mAl x cAl x ∆tAl) = (mH2O x cH2O x ∆tH2O)
We know ∆t = Tempmixture - Tempinitial, so we can substitute the data to get:
- [15.6 g x 0.899 J/g oC x (Tmix - 100oC)] = [(45.6 g x 4.184 J/g oC x (Tmix - 26.70oC)]
, PORTAGE CHEMISTRY 103 MODULE 3 EXAM STUDY QUESTIONS
AND ANSWERS ALL ANSWERS CORRECT BEST EXAM SOLUTION FOR
NURSING GRADED A+
Now, solve:
- [14.0244 J/oC x (Tmix - 100oC)] = [(190.7904 J/oC x (Tmix - 26.7oC)]
- 14.0244 Tmix + 1402.44 = 190.79 Tmix - 5094.1
6496.44 = 204.8144 Tmix
Tmix = 6496..8144 = 31.7oC
Phase change calorimetry - CORRECT ANSWERS measures the energy change occurring as a
substance changes from one phase (state) to another, such as water melting or boiling, or ice
freezing or steam condensing. In this case, no temperature change occurs, but the energy change
causes the particles of the substance to form or break intermolecular bonds and change from one
state to another. The equations used to do phase change calorimetry calculations are shown below:
Phase changes of solid to liquid or liquid to solid:
qs↔i = mass x Heat of Fusion = m x ∆Hfusion
Phase Changes of liquid to gas or gas to liquid:
ql↔g = mass x Heat of Vaporization = m x ∆Hvapor
What is the energy involved in vaporization of 200 grams of water at 100oC if the heat of
vaporization for water is 2.26 kJ/g? - CORRECT ANSWERS When energy is given off in any of these
phase changes, a negative sign is placed in front of the value, and when energy is added, a positive
sign is placed in front of the value.
ql↔g = m x ∆Hvapor = 200 g x 2.26 kJ/g = 452 kJ (since heat is added) = + 452 kJ
What is the energy involved in freezing 200 grams of water at 0oC if the heat of fusion for water is
0.334 kJ/g? - CORRECT ANSWERS ql↔s = m x ∆Hfusion = 200 g x 0.334 kJ/g = 66.8 kJ (since heat is
removed/given off) = - 66.8 kJ
How much heat is involved to convert of 20 grams of ice at -10oC to 20 grams of steam at 120 oC? -
CORRECT ANSWERS ∆Hfusion = 0.334 kJ/g (H2O(l) ↔ H2O(s))
∆Hvapor = 2.26 kJ/g (H2O(l) ↔ H2O(g))
c (water) = 4.184 J/g oC
c (ice) = 2.09 J/g oC
