Energetics & electrochemistry · SL/HL
Calorimetry
Connect heat transfer to molar enthalpy change.
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Number formats & units
Use decimal dots in datasets. Single values also accept decimal commas and scientific notation such as 1.2e-3 or 1.2 × 10⁻³.
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Result & working
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Interpretation & assumptions
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Formula & example
The relationship
What the variables mean
| Symbol | Meaning |
|---|---|
| T_final − T_initial; same numerical interval in °C or K. | |
| Amount of reaction basis used for molar enthalpy. |
Worked example
- Mass heated m / g
- 100.0
- Specific heat capacity c / J g⁻¹ K⁻¹
- 4.18
- Initial temperature / °C
- 20.0
- Final temperature / °C
- 27.5
- Amount associated with ΔH / mol
- 0.0500
-62.7 kJ mol⁻¹
Follow the example steps
- ΔT = T_f − T_i = 27.5 − (20) = 7.5 K
- q_solution = mcΔT = 100 × 4.18 × 7.5 = 3135 J = 3.135 kJ
- q_reaction = −q_solution = -3.135 kJ
- ΔH = q_reaction/n = -3.135 / 0.05 = -62.7 kJ mol⁻¹
Common mistakes
Keep joules and kilojoules consistent.
Incorrect approach
q = 1000 J, n = 0.1 mol: ΔH = −10000 kJ mol⁻¹
Correct approach
q = 1 kJ: ΔH = −1/0.1 = −10 kJ mol⁻¹
More checks before you submit
- Use the mass actually represented by the heat-capacity model.
- Keep J and kJ consistent before dividing by moles.
Method notes
The sign convention here treats heat gained by the measured surroundings/solution as heat lost by the reaction. Real calorimeters may require a calorimeter constant and correction for heat loss.