# Journal Prompt: Trusting the Numbers

A calorimetry experiment always loses some heat to the surroundings, yet chemists still trust the data enough to calculate enthalpy changes.

**Prompt: Explain how you would use calorimetry data to determine the enthalpy change of a reaction, and discuss why the calculated value might differ from an accepted value found using standard enthalpies of formation ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23641), [Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23639)).**

### Where to start:
- What does Q = mcΔt actually measure in a calorimetry setup, and what does each variable represent ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23634))?
- How is enthalpy, ΔH, defined for a chemical reaction ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23636))?
- What assumptions does a simple calorimeter make about heat loss to the surroundings?
- How would you use ΔH notation to report your result clearly ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23638))?

### Stretch:
Explain how Hess' law could let you check your experimental value against a calculated value built from other known reactions, without repeating the calorimetry ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23640)).

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*AILI prompt · language en · model claude-sonnet-5 · generated 2026-09-17 · id d0969b86-e4fd-4980-b269-2ffdfc709bf1*

### Sources

- node:n1: Unit A: Thermochemical Changes (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23632)
- node:n2: General Outcome 1 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23633)
- node:n3: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23634)
- node:n4: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23636)
- node:n5: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23638)
- node:n6: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23639)
- node:n7: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23640)
- node:n8: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23641)
- node:n9: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23643)
- node:n10: General Outcome 2 (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23650)
- node:n11: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23652)
- node:n12: Specific Outcomes for Knowledge (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/23653)