CHEMISTRY NOW: Calorimetry - Measuring Heat Energy Transfer (Grades 9-12) Print

Objective:

Students will understand the relationships between energy, temperature, and heat. Students will be able to measure energy transfer from one substance to another using a calorimeter. Through facilitated deliberation, students will design the procedure for conducting the lab and data collection.


Introduction Notes:

CHEMISTRY NOW: Calorimetry - Measuring Heat Energy Transfer

 

Subject Area: Chemistry

Grade Level:  High School Chemistry

Lesson Title: Calorimetry - Measuring Heat Energy Transfer

 

National Science Education Standards:

Science as Inquiry: 9-12

Science as Inquiry: Abilities to Do Scientific Inquiry, 9-12

Science as Inquiry: Understanding Scientific Inquiry, 9-12

 

Physical Science Education Standards:

Structure and Properties of Matter: 9-12

Conservation of Energy and the Increase in Disorder: 9-12

Chemical Reactions: 9-12

 

Life Science:

Matter, Energy, and Organization in Living Systems; 9-12

 

Suggested Prior Knowledge: heat and energy, energy changes and conservation, internal energy and the first law of thermodynamics, energy and enthalpy

 

Purpose: To conduct a class-designed experiment that will demonstrate the measurement of heat transfer from one substance to another

 

Key Vocabulary: 

 

kinetic energy- the energy of motion; EK=(1/2)mv2

 

heat- the energy transferred between two objects as a result of a temperature difference

 

specific heat- the amount of heat required per unit mass to raise the temperature of a substance by one degree

 

heat transfer- the transfer of thermal energy between two bodies due to a difference in their temperatures

 

thermal equilibrium- when the temperature of two interacting bodies become equal

 

internal energy - the energy in a system stored at the molecular level

 

system thermal energy- the kinetic energy of the particles plus the potential energy stored within the atomic bonds of a system

 

temperature - a measure of the kinetic energy of molecular motion

 

law of conservation of energy- the first law of thermodynamics states that energy cannot be created or destroyed, and the total energy of an isolated system must therefore remain constant

 

Objective:

1. Students will understand the relationships between energy, temperature, and heat.

2. Students will be able to measure energy transfer from one substance to another using a calorimeter.

3. Through facilitated deliberation, students will design the procedure for conducting the lab and data collection.

 

Materials: (each group should receive the following)

- student worksheet

- calorimeter or strong foam container with lid

- formal lab clothing, including goggles, and lab safety protocols required

- aluminum: 10-50 grams (shot or hardware fitting)

- iron: 10-50 grams (shot, wire, or pipe fitting)

- copper: 10-50 grams (shot, wire, or pipe fitting)

- thermometer

- stirring rod

- matches

- paper clip

- scale capable of measuring tenths of a gram

- hot plate

- tongs

- heat-proof gloves

- graduated cylinder

- 100ml beaker

 

Procedure:

1. Refresh concept knowledge with a discussion about energy with the class by asking them the following questions:

- What does temperature measure?

- What is heat?

- How does energy differ between a cup of water and a bathtub full of water at the same temperature?

- What variables do we need to account for when transferring heat from one object to another?

 

2. Use the discussions and conclusions from the above conversation as an introduction to a class- designed experiment that determines the thermal energy transfer in a classic calorimetry experiment.

 

3. State the challenge to the class. All lab groups will be given a variety of metals which they will heat up, and transfer the energy absorbed by each metal to an alternate substance.          Some questions to initiate the thought process include:

- How will you conduct the experiment?

- What data will need to be collected?

- What variables will you consider and account for?

- What safety concerns do we have?

- What supplies do you need?

- Do you have a hypothesis that includes terms from the key vocabulary list?

 

4. Help students along by interjecting the terms of the thermal energy formula and other key mathematical conversions as appropriate such as:

 

change in thermal energy (Q) = mass x change in temperature x specific heat (Cp)

Q = mCp∆T

1 calorie = 4.18400 joules

1 Kilogram = 1000 grams (specific heats utilize kilograms, and data collections should reflect the same)

 

5. Once a class procedure has been designed and the key vocabulary has been introduced, the experimental procedure should include and resemble the following steps:

 

a. record the mass of the metallic samples you will use in your experiment

b. place your metal samples in a beaker, add enough water to cover the samples and bring the contents to 100°C

c. record a desired volume (75-125ml) of cool (5 °C) tap water and add it to the calorimeter

d. record the initial temperature of the water in your calorimeter

e. using tongs, carefully remove the samples from the hot water and place all of them into the calorimeter (testing each sample individually would be a valid procedure as well)

f. record the final temperature (peak temperature)

g. use the thermal energy equation and the specific heat chart to calculate the change in thermal energy.

 

6. Review with students the idea of how much energy the different materials were able to hold. Discuss with students which materials hold heat the most and the least, and how this may apply to materials science and modern industries.

 

7. Finally, have students make decisions as to where error may have been introduced into the lab. The energy absorbed by the calorimeter and energy lost to the environment are common considerations but usually not included at this level of study.

 

 

 

Additional Resources:

  • http://www.watchknow.org/Video.aspx?VideoID=17223
  • http://www.chemistryexplained.com/Ge-Hy/Heat.html
  • http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html

 

Extensions:

Students may want to connect this experiment to the real world by further experimentation or research related to foods and their caloric content; the need for high caloric foods for athletes, or for developing children versus adults; materials for vehicles, including materials used in engines, motors, etc. to dissipate heat, space shuttle tiles, etc.  Students researching topics may want to produce a research product of their results, a traditional research paper, a review of the research, a PowerPoint presentation – even find appropriate videos or make their own videos.

 

Resources for Possible Extensions:

http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p012.shtml

http://www.livestrong.com/article/359653-how-to-calculate-calories-with-calorimeter/

http://www.fire.nist.gov/bfrlpubs/fire07/PDF/f07062.pdf

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Student Worksheet for Calorimetry - Measuring Heat Energy Transfer

 

 

Experiment Title: ____________________Date: ________ Name: ___________________

 

Develop a guiding question or questions for your experiment: _______________________________________________________________________

Materials: _______________________________________________________________

Procedure: 

1. ____________________________________________________________________________

 

2. ____________________________________________________________________________

 

3. ____________________________________________________________________________

 

4. ____________________________________________________________________________

 

5. ____________________________________________________________________________

 

6. ____________________________________________________________________________

 

7. ____________________________________________________________________________

 

 

 

Data:

 

Sample ID

Sample Mass

Ti

Tf

Specific Heat (Cp)

Q

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chart of Specific Heats:

 

 

What are some possible sources in this lab and how did you account for them?

________________________________________________________________________

Conclusion (use the back if necessary):

________________________________________________________________________

________________________________________________________________________

 

Practice Questions:

 

How much heat is absorbed when 500.0g of water goes from 25.0°C to 35.0°C? 20,920 J?

How much heat is absorbed when 500.0g of copper, goes from 25.0°C to 35°C? 1,930 J?