Mixing Warm and Cold Water

1. Mixing Warm and Cold Water Collecting Data using Temperature Probe Aligning with Math & Science standards Based on the Vernier lab activity

2. Outline • Goals • Apply the relationship between heat and temperature • Determine heat energy lost and heat energy gained • Determine the relationship between heat energy lost and heat energy gained • Engage: Page Keeley Assessment Probe • Explore: Video, model creation • Explain: Lab activity • Elaborate: Simulation with gas molecules • Evaluate: Compare your results with other models • Debrief

3. Engage: What do you think? From Uncovering Student Ideas in Science, Vol. 2 by Page Keeley and others

4. Explore: Create a model to describe heat • Watch the Bill Nye video • Create 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.

5. Explain: Mixing water activity • 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  T • m = mass of water used. 1.0 ml of water is 1.0 grams • Cp = specific heat capacity = 4.18 J/g°C for water • T = Tf – Ti • Put you data on the class data slide

6. 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?

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?

8. Explain: Theory • 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.

9. Elaborate: Molecular model of heat • Start Gas Properties simulation • I 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. • I add 100 molecules of gas at 100 Kelvin. • I add 100 molecules of gas at 250 Kelvin. • I add 200 molecules of gas at 100 Kelvin. • I add 300 molecules of gas at 300 Kelvin.

10. Screen shot of Gas Properties simulation

11. Evaluate: Other models of heat Select the best model of heat from the choices below and support your answer with data from the activity. • Conspicuous heat: heat is only associated with very hot bodies and large amounts of heat • Dynamic heat: heat is associated with movement • Motile heat: heat is something that spreads out from one place to another • Standard heat: any temperature above freezing is heat and any temperature below freezing is cold • Regional heat: heat is a static substance that occupies a particular volume From Making Sense of Secondary Science by Rosalind Driver and others, page 138-139

12. Evaluate: Comparing models • Show of hands for each model • How do our findings inform each model? • Conspicuous heat: even the small volume of water had heat energy • Dynamic heat: the simulation showed this to be true at the molecular level • Motile heat: the activity and the simulation showed heat energy changes within a fixed volume • Standard heat: simulation showed substances below freezing still transferred heat energy • Regional heat: heat energy comes from moving molecules

13. Brief reflection • In 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.

14. Debriefing the science teaching • Review the use of the 5 E learning cycle • Review the use of formative assessment in the lesson • Review the background knowledge required to be successful in the lesson • Discuss the use of learning progressions associated with this lesson