Open AccessThe enthalpies of combustion and formation of mono-chlorobenzoic acids
Author(s) -
Walter H. Johnson,
E.J. Prosen
Publication year - 1974
Publication title -
journal of research of the national bureau of standards. section a. physics and chemistry
Language(s) - English
Resource type - Journals
eISSN - 2376-5704
pISSN - 0022-4332
DOI - 10.6028/jres.078a.044
Subject(s) - hydrochloric acid , chemistry , combustion , calorimeter (particle physics) , standard enthalpy of formation , aqueous solution , calorimetry , carbon dioxide , heat of combustion , enthalpy , nuclear chemistry , analytical chemistry (journal) , inorganic chemistry , thermodynamics , organic chemistry , physics , detector , optics
The enthalpies of combustion of o -, m -, and p -chlorobenzoic acid have been determined in an adiabatic rotating-bomb calorimeter. The enthalpies of formation have been obtained by combination of the experimental data with the accepted values for the enthalpies of formation of water, carbon dioxide, and aqueous hydrochloric acid. The results of other investigators are discussed briefly. The resulting values and their estimated 95 percent confidence limits are as follows: o -Chlorobenzoic acid m -Chlorobenzoic acid p -Chlorobenzoic acid Δ Hc° (25 °C)-3087.91 ± 0.69 kJ/mol-3068.05 ± 1.53 kJ/mol-3064.40 ± 0.66 kJ/molΔ Hf° (25 °C)-404.83 ± 0.74 kJ/mol-424.59 ± 1.55 kJ/mol-428.16 ± 0.72 kJ/mol. Where Δ Hc ° corresponds to the process: -404.61-424.37-429.94C 7 H 5 O 2 Cl(c) + 7 O 2 (g) + 198 H 2 O(liq) → 7 CO 2 (g) + [HC1 + 200 H 2 O](liq).