Mixing Warm and Cold Water
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Transcript of Mixing Warm and Cold Water
Collecting Data using Temperature ProbeAligning with Math & Science standards
Based on the Vernier lab activity
Mixing Warm and Cold Water
GoalsApply the relationship between heat and temperatureDetermine heat energy lost and heat energy gainedDetermine the relationship between heat energy lost
and heat energy gainedEngage: Page Keeley Assessment ProbeExplore: Video, model creationExplain: Lab activityElaborate: Simulation with gas moleculesEvaluate: Compare your results with other modelsDebrief
Outline
Engage: What do you think?
From Uncovering Student Ideas in Science, Vol. 2 by Page Keeley and others
Watch the Bill Nye videoCreate a scientific model to explain what Bill Nye
said about the match and the swan sculpture.A scientific model is a description or explanation
of a concept that can be tested (if needed)Your model should include words and pictures.Think: create your model.Pair: After about three minutes, discuss your
model with a neighbor.Share: Volunteer to tell your model to the rest of
the group.
Explore: Create a model to describe heat
You and your partner(s) will be mixing water of different temperatures and determining heat transfer amounts. H is the change in heat energy of the water. Note that H can be either positive or negative.
Use the formula H = m Cp Tm = mass of water used. 1.0 ml of water is 1.0
gramsCp = specific heat capacity = 4.18 J/g°C for
waterT = Tf – Ti
Put you data on the class data slide
Explain: Mixing water activity
Adding 50 ml cold water to 25 ml of hot water
Adding 50 ml hot water to 25 ml of cold water
Adding 25 ml cold water to 50 ml of hot water
Adding 25 ml hot water to 50 ml of cold water
H for cold water (in Joules)
H for hot water (in Joules)
Explain: Class data
Questions to ponder with your partners and neighbors:
• How do the two rows of numbers compare to one another?
• What other things may have gained or lost heat energy? How did this affect the activity?
Adding 50 ml cold water to 25 ml of hot water
Adding 50 ml hot water to 25 ml of cold water
Adding 25 ml cold water to 50 ml of hot water
Adding 25 ml hot water to 50 ml of cold water
H for cold water (in Joules)
2278.14012.8
43892377.375
2685.654409.9
3406.73803.8
H for hot water (in Joules)
-3176.8-4660.7
-5434-4650.25
-5977.4-4681.6
-4075.5-5287.7
Explain: Class data Tuesday morning
Questions to ponder with your partners and neighbors:
• How do the two rows of numbers compare to one another?
• What other things may have gained or lost heat energy? How did this affect the activity?
Assuming no heat energy transfer to the environment, when two substances of different temperatures mix, the final temperature (equilibrium temperature) is between the two initial temperatures.
The equilibrium temperature depends on the mass (m), the initial temperature and the type (Cp ) of each substance.
The heat energy gained by one substance equals the heat energy lost by the other substance. Or:
mhot (Cp )hot Thot + mcold (Cp )cold T cold = 0“Hot” and “cold” are relative terms. 100°C is cold
compared to 200°C.
Explain: Theory
Start Gas Properties simulationI will initially pump 100 molecules of gas at
200 Kelvin into the box. (note: the temperature is a measure of the kinetic energy of the molecules). Predict what will happen to the final temperature in the following separate situations.a) I add 100 molecules of gas at 100 Kelvin.b) I add 100 molecules of gas at 250 Kelvin.c) I add 200 molecules of gas at 100 Kelvin.d) I add 300 molecules of gas at 300 Kelvin.
Elaborate: Molecular model of heat
Screen shot of Gas Properties simulation
Select the best model of heat from the choices below and support your answer with data from the activity.
A. Conspicuous heat: heat is only associated with very hot bodies and large amounts of heat
B. Dynamic heat: heat is associated with movementC. Motile heat: heat is something that spreads out
from one place to anotherD. Standard heat: any temperature above freezing is
heat and any temperature below freezing is coldE. Regional heat: heat is a static substance that
occupies a particular volume
Evaluate: Other models of heat
From Making Sense of Secondary Science by Rosalind Driver and others, page 138-139
Show of hands for each modelHow do our findings inform each model?
A. Conspicuous heat: even the small volume of water had heat energy
B. Dynamic heat: the simulation showed this to be true at the molecular level
C. Motile heat: the activity and the simulation showed heat energy changes within a fixed volume
D. Standard heat: simulation showed substances below freezing still transferred heat energy
E. Regional heat: heat energy comes from moving molecules
Evaluate: Comparing models
Brief reflectionIn the note card, write
down one or two things your like to discuss about the lesson during the debriefing time.
This can include, but is not limited to: content, teaching methods, the 5E learning cycle, assessment, etc.
Discuss this with your neighbor.
Review the use of the 5 E learning cycleReview the use of formative assessment in
the lessonReview the background knowledge required
to be successful in the lessonDiscuss the use of learning progressions
associated with this lesson
Debriefing the science teaching