Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box
Helmholtz and Gibbs function (or energy) differences, Helmholtz and Gibbs function (or energy) differences, ΔA and ΔG, are often invoked by their signs to describe conditions of spontaneity, nonspontaneity, and equilibrium in chemical reactions. While their differences are necessary conditions to es...
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| Format: | Journal Article |
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American Chemical Society
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/36800 |
| _version_ | 1848754870671114240 |
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| author | Glasser, Leslie |
| author_facet | Glasser, Leslie |
| author_sort | Glasser, Leslie |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Helmholtz and Gibbs function (or energy) differences, Helmholtz and Gibbs function (or energy) differences, ΔA and ΔG, are often invoked by their signs to describe conditions of spontaneity, nonspontaneity, and equilibrium in chemical reactions. While their differences are necessary conditions to establish these behaviors, they are insufficient because they do not apply to local situations where differential values, dA and dG, are appropriate. We here show that the differences are fully meaningful quantities, being important in examining overall reaction, such as in chemical synthesis, where dA and dG may be irrelevant. Interpretation of the differences is readily understood in terms of the van’t Hoff reaction box in which reactants are converted to products, without reference to kinetics or mechanisms, and products are extracted as independent materials, each under their own specified conditions. This behavior can be attained in practical situations where a product can be extracted in a phase separate from the reactants, such as a single gas, an immiscible liquid, a precipitate, a new pure solid phase, or even in an electrochemical or fuel cell. This is illustrated in the case of the Haber–Bosch industrial process for the production of ammonia., are often invoked by their signs to describe conditions of spontaneity, nonspontaneity, and equilibrium in chemical reactions. While their differences are necessary conditions to establish these behaviors, they are insufficient because they do not apply to local situations where differential values, dA and dG, are appropriate. We here show that the differences are fully meaningful quantities, being important in examining overall reaction, such as in chemical synthesis, where dA and dG may be irrelevant. Interpretation of the differences is readily understood in terms of the van’t Hoff reaction box in which reactants are converted to products, without reference to kinetics or mechanisms, and products are extracted as independent materials, each under their own specified conditions. This behavior can be attained in practical situations where a product can be extracted in a phase separate from the reactants, such as a single gas, an immiscible liquid, a precipitate, a new pure solid phase, or even in an electrochemical or fuel cell. This is illustrated in the case of the Haber–Bosch industrial process for the production of ammonia. |
| first_indexed | 2025-11-14T08:47:17Z |
| format | Journal Article |
| id | curtin-20.500.11937-36800 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:47:17Z |
| publishDate | 2016 |
| publisher | American Chemical Society |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-368002017-09-13T15:19:35Z Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box Glasser, Leslie Helmholtz and Gibbs function (or energy) differences, Helmholtz and Gibbs function (or energy) differences, ΔA and ΔG, are often invoked by their signs to describe conditions of spontaneity, nonspontaneity, and equilibrium in chemical reactions. While their differences are necessary conditions to establish these behaviors, they are insufficient because they do not apply to local situations where differential values, dA and dG, are appropriate. We here show that the differences are fully meaningful quantities, being important in examining overall reaction, such as in chemical synthesis, where dA and dG may be irrelevant. Interpretation of the differences is readily understood in terms of the van’t Hoff reaction box in which reactants are converted to products, without reference to kinetics or mechanisms, and products are extracted as independent materials, each under their own specified conditions. This behavior can be attained in practical situations where a product can be extracted in a phase separate from the reactants, such as a single gas, an immiscible liquid, a precipitate, a new pure solid phase, or even in an electrochemical or fuel cell. This is illustrated in the case of the Haber–Bosch industrial process for the production of ammonia., are often invoked by their signs to describe conditions of spontaneity, nonspontaneity, and equilibrium in chemical reactions. While their differences are necessary conditions to establish these behaviors, they are insufficient because they do not apply to local situations where differential values, dA and dG, are appropriate. We here show that the differences are fully meaningful quantities, being important in examining overall reaction, such as in chemical synthesis, where dA and dG may be irrelevant. Interpretation of the differences is readily understood in terms of the van’t Hoff reaction box in which reactants are converted to products, without reference to kinetics or mechanisms, and products are extracted as independent materials, each under their own specified conditions. This behavior can be attained in practical situations where a product can be extracted in a phase separate from the reactants, such as a single gas, an immiscible liquid, a precipitate, a new pure solid phase, or even in an electrochemical or fuel cell. This is illustrated in the case of the Haber–Bosch industrial process for the production of ammonia. 2016 Journal Article http://hdl.handle.net/20.500.11937/36800 10.1021/acs.jchemed.5b00925 American Chemical Society restricted |
| spellingShingle | Glasser, Leslie Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title | Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title_full | Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title_fullStr | Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title_full_unstemmed | Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title_short | Correct Use of Helmholtz and Gibbs Function Differences, ?A and ?G: The van’t Hoff Reaction Box |
| title_sort | correct use of helmholtz and gibbs function differences, ?a and ?g: the van’t hoff reaction box |
| url | http://hdl.handle.net/20.500.11937/36800 |