Lesson Write-Up For Winter Quarter 2012
Your name: David Luong
Title of Lesson: [CSI: A Heated Investigation]
Grade Level: 11th-12th
Subject(s): Physics, Chemistry
Summary:
Students are asked to solve a crime by determining specific heat capacity values for metal pieces. The primary topic covered is heat transfer between a hot and cold object. Students will make initial and final temperature measurements of a hot metal object placed in a cup of water and determine the specific heat capacities of two different metals.
Time Required: 50 minutes
Group Size: 2-3
Cost to implement:
The major cost comes from the digital thermometers and portable stove. The other items can be bought at supermarkets or borrowed from a chemistry classroom.
Learning Goals:
After this lesson, students should be able to:
· Understand heat flows from a hot source to a cold source
· Recall the equation for heat transfer between two objects
· Define that an object’s heat capacity means how much units of heat energy is needed to raise 1 kilogram of that object by 1 degree Celcius.
Level of Inquiry:
The lesson has questions embedded into the protocol to help remind the students of the procedure’s significance. Students will also have debriefing questions to test their understanding.
Introduction / Motivation:
Students are hooked into the lesson by being asked to help crime scene investigators solve a case. Tell students they need to be debriefed before starting the investigation. Inform students that they will need to use their knowledge of physics and chemistry to solve this crime, much like how real-world detectives do on a daily basis.
Lesson Background Concepts for Teachers:
Explain the concept that heat flows from a hot source to a cold source, and the equation that describes how much heat is lost or gained. Explain each term. Explain that in a calorimeter, the heat gained is equal to the heat lost so we can setup an energy balance between a hot and cold object. By measuring the masses of each heat exchange medium and their initial and final temperatures, we can figure out one object’s heat capacity if we know the other. Hot metal pieces with unknown heat capacities transfer heat to room temperature water (and every good detective knows the heat capacity of water is 4186 J/kg degC)
Procedure:
1. Go to the balance and measure the mass of your Styrofoam cup.
2. Go to water station and fill your Styrofoam cup with about 200 mL of water using the beaker.
3. Go to the balance again and measure the mass of the cup + water combination.
a. Determine the mass of the water and also measure the initial temperature of the water.
4. Go to the evidence center (where the boiling pot of water is) and you will find the metal pieces boiling in water.
a. What is the initial temperature of the metal piece? You should know without using a thermometer. Verify with thermometer.
b. Using the tongs, carefully place the metal piece in your cup of water and use aluminum foil to cover your cup.
5. Go to your lab station and gently stir the water. Wait a few minutes for both the water and metal to reach a common temperature and record it.
a. Why do we stir the cup? ______
b. Why do we cover the cup?______
6. Repeat for the other metal. If you had metal A before, now use the metal B and vice versa. Keep the metal piece you just used at your lab station.
7. Do this step after doing steps 1-6 with both metal A and B. Go to the balance and measure the masses of the two metal pieces.
8. Go to your lab station and solve for the specific heat capacity of the metal pieces.
9. IMPORTANT: Return your thermometer to your lead Agent (teacher) before you leave the crime lab.
Materials List
· 2 different metal pieces (aluminum and steel work well), labeled A and B
· Digital thermometer to easily read temperatures
· Styrofoam cup
· Stirrer
· Aluminum foil to cap the cup
· Water, boiling and at room temperature
· Beaker or pot
· Hot plate or portable stove
· Tongs
Each group will need:
· Refer to material list
To share with the entire class:
· Beaker to measure water
· Pot to heat metals
· Hot plate or portable stove (with gas canisters to last through all the classes)
· Boiling water
· Tongs
Safety Issues:
· Boiling water
Lesson Closure:
If time permits, create a results table on the board and have each group write down their values of heat capacities along with their conclusion of who is guilty of the crime. As a class, ask them the following debriefing questions:
1. Who do you conclude committed the crime? Do the lab results clearly indicate this?
2. Explain what causes heat to flow.
3. What does it mean for something to have a high specific heat capacity? Given 1 kg of that something, does it increase in temperature easily or not? Explain.
4. What are the possible errors in the crime investigation today?
Assessment:
Pre-Activity Assessment:
Ask students what they know about heat. Ask them about personal experiences of sitting on a cold bench or boiling water in the kitchen. Ask them how does heat flow in these situations and why some objects stay hot or cold for a long time e.g. brick, water while other objects do not e.g. ice cream.
Activity Embedded Assessment:
Walk around the classroom and ask students about the lab’s setup. Some questions may include:
· Why do we use Styrofoam cups and how is it similar to a calorimeter?
· Why do we use stirrers?
· Why do we use aluminum foil to cap the cup?
Post-Activity Assessment:
Ask students for answers to the debriefing questions and perform the Lesson Closure.
Is this lesson based upon or modified from existing materials? If yes, please specify source(s) and explain how related:
This lesson was created with originality.
References: none
Attachments:
· Heat Capacity for Students.doc
List CA Science Standards addressed:
· Students know heat flow and work are two forms of energy transfer between systems.
· Students know how to solve problems involving heat flow, work, and efficiency in a heat engine and know that all real engines lose some heat to their surroundings.