An Application of Context- and Problem-Based Learning (C-PBL) into Teaching Thermodynamics

Abstract

This study aims to investigate the applicability of context- and problem-based learning (C-PBL) into teaching thermodynamics and to examine its influence on the students’ achievements in chemistry, retention of knowledge, students’ attitudes, motivation and interest towards chemistry. The embedded mixed method design was utilized with a group of 13 chemistry students in a 2-year program of “Medical Laboratory and Techniques” at a state university in an underdeveloped city at the southeastern region of Turkey. The research data were collected via questionnaires regarding the students’ attitudes, motivation and interest in chemistry, an achievement test on “thermodynamics” and interviews utilized to find out the applicability of C-PBL into thermodynamics. The findings demonstrated that C-PBL led a statistically significant increase in the students’ achievement in thermodynamics and their interest in chemistry, while no statistically significant difference was observed in the students’ attitudes and motivation towards chemistry before and after the intervention. The interviews revealed that C-PBL developed not only the students’ communication skills but also their skills in using time effectively, making presentations, reporting research results and using technology. It was also found to increase their self-confidence together with the positive attitudes towards C-PBL and being able to associate chemistry with daily life. In light of these findings, it could be stated that it will be beneficial to increase the use of C-PBL in teaching chemistry.

Appendices

Appendix 1 (Learning Outcomes)

Learning Outcomes

• 1. Realizes the importance of the relationship between system and surrounding

• 2. Classifies systems with the variables of heat exchange, temperature, pressure and volume

• 3. Explains the internal energy of a system on the basis of atoms/molecules

• 4. Associate the internal energy of the constant volume and constant pressure systems with the mechanical energy and heat exchange.

• 5. Describes the first law of thermodynamics

• 6. Gives examples to the field of thermodynamics applications in daily life

• 7. Explains the enthalpy change (dH) via reaction temperature (qp)

• 8. Relates the reaction enthalpy changes with “standard formation enthalpy changes”

• 9. Correlates the enthalpy change of a reaction with intermediate steps of enthalpy change

• 10. Establishes a relationship between the enthalpy changes in chemical reactions and the bond energies

• 11. Examines the concept of spontaneous/nonspontaneous change

• 12. Explains spontaneous processes tend to achieve a state of minimum energy and gives examples

• 13. Gives examples to spontaneous changes that do not meet the minimum energy

• 14. Explains the concept of entropy, on the basis to “thermal energy” and “probability”

• 15. Establishes a relationship between entropy changes (ΔS) and the spontaneity

• 16. Interprets the second and third laws of thermodynamics

• 17. Describes the total entropy change of the system and the universe via “Gibbs free energy”

• 18. Examines the spontaneity of chemical reactions via Gibbs free energy

Appendix 2 (The Content Covered in Thermodynamics)

The Curriculum in Thermodynamics

• 1. Systems and types of energy

  • (a) System and surrounding

  • (b) Internal energy

  • (c) Heat and work

  • (d) The first law of thermodynamics

• 2. Enthalpy and changes in the system

  • (a) Enthalpy

  • (b) Standard formal energy

  • (c) Hess’s law

  • (d) Bound energy

• 3. Spontaneity

  • (a) Spontaneous and nonspontaneous processes

  • (b) The second and third laws of thermodynamics

  • (c) Gibbs free energy

  • (d) The relation between the spontaneity of system and Gibbs free energy

Appendix 3 (Sample Scenario)

Stove and Carbon Monoxide Poisoning

On a cold winter day Mrs. Emine wants to make tea on a coal stove, so she puts 3 kilos of coal into the stove and ignites the coal. She puts the tea pot onto the heater.

After a while, her daughter Derya comes home from school and sits by the stove, stretches her hands towards it to warm up a little after a stormy snowy day. Seeing the boiling teapot on the stove, she thinks "how it is possible that a little heater like this can warm up the whole room and boil the water in the pot". She falls asleep by the hot stove. After a while she wakes up and feels the room and herself cold and thinks, "why nobody did invented a coal that burns out forever". She brings three more kilos of coal and fills up the stove and lies down on the cushion by the stove. After a while Mrs. Emine backs to home and sees her daughter sleeping by the stove, and calls on her. When her daughter does not respond, she goes to her and tries to wake her up. Despite all her efforts, she can’t wake her up, and immediately calls emergency. When the health care team arrives and examines Derya, they diagnose that she suffers from carbon monoxide poisoning. They take Derya to a hospital for treatment.

Considering the story above, please answer the following questions. You can make use of the internet, course books and other recourses to make comprehensive and extensive explanations.

• 1. What is the reason for Derya’s poisoning and how does this poisoning happen?

• 2. How the heating takes place? What kind of energy transfers and how this energy transfers take place between the stove and its surrounding?

• 3. Write the reaction that accompany to the coal burning and balance the reaction. Calculate enthalpy changes accompanying to the 3 kg of coal burning. Accept the formula and molecular weight of coal as C135H96O9NS, Ma= 1906 g.mole-1.

• 4. Other than coal what other alternative fossil energy sources can be used for heating, and what are the reactions that accompany during their burning? What is the enthalpy changes accompanying to the 1 kg of these fuels and compare them with the coal?

• 5. What do you think about the possibility of producing an ever burning coal? Discuss this question considering the first law of thermodynamics?