Educ 398 Inquiry-based Lesson Plan
Unit:
Terri Thunder
Physical Science 20 Heat
Date: November 17, 2014
Lesson Title: Exploring Heat of Solutions of Various Substances
Time Allotted: 55 min
Overview: Curriculum and Learning Contexts
Goals: Lesson aides in the development the following areas of the Scientific Literacy Framework.
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STSE: Relationship between science and technology
Knowledge: Physical Science – Matter and Energy
Skills: Performing and Recording; Analyzing and Interpreting; Communication and Teamwork
Attitudes: Collaboration; Safety; Inquiry in Science; Appreciation of Science; Interest in Science
Outcomes: PS20-HT2 Determine experimentally the quantities of heat involved in chemical reactions
Indicators: By the end of the lesson, students should be able to:
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Distinguish between exothermic and endothermic chemical reactions
Measure, using a thermometer or temperature probe, and record the temperature
change in an exothermic and/or endothermic chemical reaction
Discuss the importance of analyzing the quantities of heat involved in chemical reactions
Calculate the molar heat of reaction of dissolving ionic compounds in a solution
Context: This lesson can be used in the middle of the unit after covering most of the indicators from
PS20-HT1
Materials and Safety Considerations
Materials
Styrofoam cups (3 per group)
Thermometers
Deionized water
100 mL graduated cylinder
Weigh boats or paper
Spatula/scoopula
Weighing device
Stir rods or stir plate(with stir bar)
Ammonium nitrate (NH4NO3)
Calcium chloride (CaCl2)
Sodium acetate (NaC2H3O2)
Magnesium sulfate (MgSO4)
Potassium nitrate (KNO3)
Potassium chloride (KCl)
Safety Considerations
Safety goggles
Proper chemical disposal
Management Considerations
 Ensure students designate roles
in their groups (ie. data
recording, set-up, ‘technician’)
 Temperature readings are not
taken with thermometer
touching sides of coffee cup
Procedure: Described in context with the lesson plan below as it is determined by student group
decisions.
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Educ 398 Inquiry-based Lesson Plan
Terri Thunder
Introduction
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Pass around examples of hot packs and cold packs; relate to heat and temperature covered in
previous lessons (ie. increasing heat results in increasing temperature)
o If not, then ask for definition of heat. Heat should be discussed as a form of energy.
Ask students to define what cold is.
Discuss how some processes or reactions will produce heat or consume heat
o When we feel heat or increase in temperature, heat is flowing into our hands
o When we feel cold or decrease in temperature, heat is flowing away from our hands
o We can determine heat quantitatively using thermometers!
Most cold and hot packs are made by the chemical process of dissolving salts
o If we are only working with water and salt, what can we vary to change temperature?
o Answer you are looking for is volume of water and amount of salt (ie. mass)
Students will design and make their own hot packs and cold packs; as a class, they will determine
appropriate substance and mass of substance for an effective hot pack and cold pack
o Will span over two lessons; this lesson students determine appropriate substance and
substance mass needed to reach target temperature of their hot pack or cold pack
o Students will then use their data collected from this class to design their hot pack or cold
pack next class.
Introduce set-up of coffee-cup calorimeter and show how to use it
o Students can use this time to assemble their coffee-cup calorimeter
 nest one cup in another, and rip the rim off the third so it can function as a lid
 students need to put a hole in the lid for their thermometer to fit
 instruct students that when they do their experiment, they need to gently swirl the
contents so as not to splash too much and to allow for complete dissolution and
aide in mixing
o Ask why we should use Styrofoam vs beakers
 Styrofoam insulates and we don’t lose as much heat to the surrounding air and
counter; reason why we also have a cover for our set-up
o Why do we need to swirl the water while taking the initial temperature and after adding our
chemical?
 Temperature reading of thermometer is more accurate
 Remind students that when they record their max. temperature, they need to allow
a few seconds for it to stabilize – shouldn’t drop or increase
Development of Science Concepts and Skills
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Students will be divided into groups of 3-5 (depending on size of class) and each group will get to
choose one substance to investigate
Students will investigate effect of mass on temperature change of water; record in a table and put
into graph form (“Temperature vs Mass of Substance”)
o Students need to plan their procedure before they can begin
o Max. mass should be 10 g (but this depends on amount of chemicals you have at hand – cost
of chemical)
o As a class, decide on volume of water that should be used – they want their hot packs and
cold packs to be transportable! (ie. 50 – 100 mL)
Students will report their results on the board; as a class, determine which substances are
appropriate for cold packs and which for hot packs
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Educ 398 Inquiry-based Lesson Plan
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Terri Thunder
Ask what temperature change they were measuring – answer you are looking for is water!
Introduce heat flow between system and surroundings
o Ask if temperature of water increased, where did that heat flow from? (answer: Salt)
o If temperature of water decreased, where did that heat flow to? (answer: salt)
o Heat flowing out of the system is exothermic and heat flowing into the system is
endothermic; these terms are from the “system’s point of view”
Introduce calorimeters; what we used was a model of a calorimeter – used to measure heat
Heat = q
q = m·C·T
where m = mass of substance, C = specific heat capacity of substance, and
T = change in temperature = Tf - Ti
- qsystem = qsurroundings
In our case, -qsolution = qwater
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because we will assume the involvement of our calorimeter in
heat flow is small enough to be negligible, otherwise
qsurr = qcal + qw
The change in temperature of water is due to the change in enthalpy of reaction (H) (or heat
transfer)
For our case, qsoln = Hsoln·n
where n = moles of substance
Rearrange to calculate molar enthalpy (molar heat of reaction):
Hsoln = qsoln  n
o
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These calculations can only be done after Foundations of Chemistry unit in Physical Science
20 -- Students should know how to determine moles
o Connect value of H to endothermic and exothermic
 -H is exothermic and +H is endothermic
Discuss importance of measuring heat in context of hot packs and cold packs
o Students should see the connection between enthalpy and temperature change by seeing
relationship between H and q
o What temperature do you want to reach with a hot pack or cold pack?
o To reach the temperature you want, what mass of substance would you need? Is this
practical or reasonable for your hot/cold pack?
o NOTE: when designing their hot pack and cold pack, students should aim for complete
dissolution of their salt
o Allow students time to discuss in their groups whether they want to make a cold pack or hot
pack, and what temperature they would like to reach.
 Max. 55°C and min. 3°C
Closure and Assessment
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Students will be assessed during the activity through use of guiding questions to determine their
grasp of the concepts of heat
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Educ 398 Inquiry-based Lesson Plan
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Terri Thunder
Students will also be assessed on their data table, graph, subsequent calculations of heat and
change in enthalpy, and
Students will apply these skills and knowledge when they determine the ideal mass of substance to
reach their desired temperature
o Students will have time next class to complete these calculations if they have not finished
o Before they can make their hot /cold pack, their calculations will be checked
Additional Notes
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A super saturated solution of sodium acetate can be used to demonstrate exothermic process as a
result of lattice formation (plus it looks cool) – can simply use it to demonstrate to show the
students what happens inside the hot packs with the metal disk that is snapped to activate it
Students can carefully swirl the contents of their coffee-cup calorimeter rather than use a stir rod
Adaptations to consider when students design their hot/cold pack:
o Can ask the students to consider material cost of their hot/cold pack
o Ask students to consider safety of their chemical should their hot/cold pack burst
Ask students for sources of error or discuss as a class
Can connect to the formation of bonds or breaking of bonds
o Relate to intermolecular formations since this activity is looking at dissolution of salts
o Forming bonds releases energy and breaking bonds requires energy
 Can relate this to photosynthesis and cellular respiration
o If more bonds are broken than formed, then there is an overall consumption of energy
(endothermic process)
o If more bonds are formed than broken, then there is an overall release of energy
(exothermic process)
o Our body temperature is maintained due to chemical reactions occurring in our body
 Result of metabolizing the food we eat
References
1. Bartole-Scott, A. (2010). Chemistry 114.3 laboratory manual 2010-2011 - Department of Chemistry
University of Saskatchewan: General chemistry for engineers. Plymouth, MI: Hayden-McNeil
Publishing.
2. Risko, C. (n.d.). Hot and cold packs: A thermochemistry activity. Retrieved from
http://www.carolina.com/teacher-resources/Interactive/hot-and-cold-packs-a-thermochemistryactivity/tr29415.tr
3. Gosser, D. K., Strozak, V. S., & Cracolice, M.S. (2001). Peer-led team learning general chemistry: The
workshop project. Upper Saddle River, NJ: Prentice-Hall, Inc.
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Educ 398 Inquiry-based Lesson Plan
Terri Thunder
Discussion of Rationale
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This activity was chosen because it allows room for student contribution to planning so that it is not
entirely a scripted activity, and it also connects to real-life (ie. instant single-use thermal packs)
Reinforces difference between heat and temperature (q = mCT)
o Connect terms of endothermic and exothermic to how reactions or processes feel (warm vs
cool)
This activity will provide students opportunity to reinforce definition of heat and allow the students
to later connect with first law of thermodynamics (energy is neither created nor destroyed)
qsystem = -qsurroundings
o Can also connect with historical develops of thermodynamics (ie. first calorimeter)
It allows students opportunity to contribute their findings to the scientific community of the
classroom, modelling the collaborative efforts in research
This activity also allows introduction of change of enthalpy (H) and provides opportunity to relate
to the heat flow between system and surrounding, which often times is a difficult concept for
students to grasp
I thought this activity was a good transition between learning about heat involved in changes of
state and heat involved in chemical reactions
o Depending on how the unit is structured, this would also be a good introduction to
calorimetry and use of calorimeters, since some indicators in PS20-HT1 also involve use of
calorimeters in measuring specific heat capacities (ie. water, metals)
o Or, it could be used to reinforce knowledge of calorimeters if specific heat capacities are
determined prior to this lesson
Additionally, this activity and lesson allow broad development across the various learning contexts
for scientific literacy (ie. STSE, Attitudes, Skills, Knowledge)
This activity and lesson provide opportunity for future lessons that cover remaining indicators of
PS20-HT2, namely the indicator that requires students to design, create, and evaluate effectiveness
of a cold/hot pack
o use of graphs will allow students to determine through extrapolation or best-fit line the
mass of substance required to reach their desired temperature – provides opportunity to
apply and further develop their analyzing and interpreting skills
o This also involves application of their stoichiometry knowledge since the design of the hot
pack and cold pack requires complete dissolution of ionic compound
 For this reason, this portion of Foundations of Chemistry should be covered first so
that this activity is more effective
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