Discussion Overview
The discussion revolves around the definition of heat and its relationship to the First Law of Thermodynamics, particularly focusing on discrepancies arising from different conventions used in physics and chemistry regarding work and heat transfer. The scope includes theoretical definitions and conceptual clarifications.
Discussion Character
- Conceptual clarification
- Debate/contested
Main Points Raised
- Zemansky defines heat in terms of energy transferred by non-mechanical means, leading to a formula: Q = ΔU - W (diathermic), which contrasts with the First Law of Thermodynamics: Q = ΔU + W.
- Some participants note that the discrepancy may arise from the convention used regarding whether W represents work done by the system or on the system.
- A participant outlines the conventions in physics, stating that heat absorbed by the system corresponds to work done on the system, while heat released corresponds to work done by the system.
- Another participant mentions that in chemistry, the conventions are reversed, prompting questions about whether this reversal is merely by convention or serves a specific purpose.
- It is noted that different texts may adopt different conventions, with one participant referencing Denbigh's chemistry text as using the physics convention.
- Clarification is provided that in the physics convention, W is the work done by the surroundings on the system, while in the chemistry convention, W is the work done by the system on the surroundings, independent of the process direction (expansion or compression).
Areas of Agreement / Disagreement
Participants express uncertainty regarding the existence of an official set of guidelines from IUPAC or a clear consensus in the physics and chemistry communities about these conventions. The discussion remains unresolved regarding the implications of these conventions.
Contextual Notes
The discussion highlights the dependence on definitions and conventions used in different contexts, which may lead to misunderstandings or discrepancies in interpreting the First Law of Thermodynamics and the definition of heat.