# Enthalpy Changes and Calorimetry

## Task

Students present a labelled model or report on enthalpy changes and calorimetry.

## Curriculum alignment

Students demonstrate achievement of the following outcomes:

- Define enthalpy and molar enthalpy for chemical reactions ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23636))
- Recall the application of Q = mcΔt to the analysis of heat transfer ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23634))
- Use calorimetry data to determine the enthalpy changes in chemical reactions ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23641))
- Use and interpret ΔH notation to communicate and calculate energy changes in chemical reactions ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23638))

## Rubric

| Criterion | Beginning | Developing | Proficient | Exemplary |
|-----------|-----------|-----------|-----------|-----------|
| **Definition and notation** | Attempts to define enthalpy or ΔH notation with significant gaps or errors. | Defines enthalpy and ΔH notation with minor omissions or imprecision. Partial understanding evident. | Defines enthalpy and molar enthalpy clearly. Uses ΔH notation correctly in calculations and communication. | Defines enthalpy and molar enthalpy with precision. Applies ΔH notation fluently across multiple contexts and calculations. |
| **Heat transfer calculation** | Applies Q = mcΔt with errors in formula use, unit conversion, or variable identification. | Applies Q = mcΔt mostly correctly. Minor errors in calculation or unit handling. Shows understanding of variables. | Applies Q = mcΔt correctly to analyse heat transfer. Converts units accurately. Identifies all variables appropriately. | Applies Q = mcΔt with accuracy and efficiency. Explains the role of each variable. Handles complex unit conversions seamlessly. |
| **Calorimetry data analysis** | Attempts to use calorimetry data but analysis is incomplete or contains major errors in logic. | Uses calorimetry data to determine enthalpy changes with minor computational or conceptual errors. | Uses calorimetry data accurately to determine enthalpy changes. Calculations are correct and method is clearly shown. | Analyses calorimetry data with precision. Determines enthalpy changes correctly. Identifies and addresses experimental limitations or sources of error. |
| **Model or report clarity** | Model or report is disorganized. Labels are missing or inaccurate. Explanations lack clarity. | Model or report is mostly organized. Most labels are present and accurate. Explanations are generally clear but lack some detail. | Model or report is well-organized and clearly labelled. Explanations are logical and support the chemistry concepts. | Model or report is exceptionally clear and well-labelled. Explanations are thorough, logical, and demonstrate deep conceptual understanding. |

## Scoring

Assign each criterion a level: Beginning (1), Developing (2), Proficient (3), or Exemplary (4).

A total of 4–7 indicates beginning/needs intervention; 8–11 indicates developing performance; 12–14 indicates proficient performance; 15–16 indicates exemplary performance.

## Notes for the teacher

- **Consistency in calculation assessment.** When marking Q = mcΔt application, verify that the student has correctly identified the mass of the substance that absorbs or releases heat (usually water in a calorimeter), not the mass of the fuel or reactant. This is a common source of error. For example, if a student burns 2 g of ethanol in a calorimeter and heats 100 g of water by 5 °C, use m = 100 g (water) and ΔT = 5 °C in Q = mcΔt, not the mass of the fuel.

- **Calorimetry context.** Accept models or reports based on combustion calorimetry ([Resource](https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/9ykNTynh306g6EnZlkTITQ)) or solution calorimetry ([Resource](https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/0uxhxD914kqzmssVwCK4tg)). The method differs, but the principle of using Q = mcΔt to find ΔH remains the same. Assess the logic of the method chosen, not adherence to a single procedure.

- **ΔH sign convention.** Students must use negative ΔH for exothermic reactions and positive ΔH for endothermic reactions. Check that the sign is justified by the data or explanation, not guessed. If a student calculates Q correctly but assigns the wrong sign to ΔH, mark the criterion "Definition and notation" as Developing at best.

- **Labelling standards.** For models, require labels for reactants, products, energy released or absorbed, and the calorimeter components (if shown). For reports, require a clear statement of the reaction studied, the measured temperature change, and the calculated ΔH with units.

---
*AILI marking guide · language en · model claude-haiku-4-5-20251001 · generated 2026-09-17 · id 9751bf9c-dd2e-4c28-b1a9-8269e1b2e47d*

### Sources

- node:n1: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23636)
- node:n2: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23634)
- node:n3: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23641)
- node:n4: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23634)
- node:n5: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23636)
- resource:r1: Resources › type#activity › SCN3796 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/9ykNTynh306g6EnZlkTITQ)
- node:n6: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes › General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23638)
- node:n7: Chemistry › Chemistry (20, 30) › Chemistry 30 › Unit A: Thermochemical Changes (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23633)
- resource:r2: Resources › type#activity › SCN3796 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/0uxhxD914kqzmssVwCK4tg)