Thermochemistry: Energy of Processes
Overview/Rationale
This unit focuses on the processes that take place when energy is added to a system. The properties of liquids and solids are studied, in addition to the properties of solutions that are formed when solids and liquids are combined. Phases are related to the intermolecular forces that exist between particles. Students analyze the graphs of phase diagrams and heating curves. Quantitatively, students perform heat (thermal energy) calculations associated with temperature and phase changes during calorimetry experiments.
Student Objectives
· Differentiate between intermolecular and intramolecular forces.
· Analyze how intermolecular forces influence the boiling and melting point of a substance, and therefore its phase at room temperature.
· Compare and contrast the properties of gases, liquids, and solids.
· Interpret graphs that depict phase changes.
· Analyze why the freezing point and boiling point of a solution are different from the properties of the pure solvent in terms of interactions at the molecular level.
· Predict the temperature change of a substance based on its specific heat.
· Calculate the thermal energy that is required to change the temperature or phase of a substance.
· Use a calorimeter to analyze the thermal energy changes that take place within a system.
Vocabulary
Intermolecular forces, intramolecular forces, surface tension, solution, solute, solvent, dilute, concentrated, concentration, volatile, non-volatile, electrolyte, colligative properties, freezing point depression, boiling point elevation, phase change, state of matter, phase diagram, triple point, critical point, heating curve, heat (thermal energy), calorie, Joule, vaporization, evaporation, boiling, condensation, freezing, melting, calorimeter, specific heat, heat of vaporization, heat of fusion, exothermic, endothermic
Department Activities:
1. Intermolecular Forces Inquiry: POGIL paper activity or Water exploration lab activity
Water activity (4 parts): https://drive.google.com/open?id=0B0XImXxS1gxJa292d0w0eC1aZjQ
2. Mixtures exploration: Students make simple mixtures to observe the resulting volume, temperature.
Conceptual: https://drive.google.com/open?id=0B0XImXxS1gxJSTVBTllxTUhVc2c
Quantitative (solution concentration calculations): https://drive.google.com/open?id=0B0XImXxS1gxJdHdDeDhnOFJQdUU
3. Calorimetry lab: Students identify metals using calorimetry to calculate the specific heat of the metal. https://drive.google.com/open?id=0B0XImXxS1gxJVHlUSW1Qalo0eFU
4. Calorimetry application lab: Students design a lab using calorimetry. Options include: Determining the calorie content of snack food (such as cheese doodles or potato chips) or analyzing the energy needed to melt ice.
Food Calories: https://drive.google.com/open?id=0B0XImXxS1gxJbC1ZTElKRHhSUnM
Melting ice: https://drive.google.com/open?id=0B0XImXxS1gxJemJ3UXZMempCeDg
Three calorimetry challenges: Lesson: http://ngss.nsta.org/Resource.aspx?ResourceID=59 , Lab handout: https://drive.google.com/open?id=0B0XImXxS1gxJUHl4Uk52VG9iWU0