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Thus, an endothermic reaction generally leads to an increase in the temperature of the system and a decrease in that of the surroundings. [1] The term was coined by 19th-century French chemist Marcellin Berthelot. [3] The term endothermic comes from the Greek แผνδον (endon) meaning 'within' and θερμ- (therm) meaning 'hot' or 'warm'. [4]
Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling. A reaction may release or absorb energy, and a phase change may do the same. Thermochemistry focuses on the energy exchange between a system and its surroundings in the form of heat. Thermochemistry is ...
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H โ, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript โ {\displaystyle \ominus } means "standard".
In thermochemistry, a thermochemical equation is a balanced chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with Δ H {\displaystyle \Delta H} In variable form, a thermochemical equation would appear similar to the following:
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter : solid , liquid , and gas , and in rare cases, plasma .
If the net enthalpy change is negative (<), the reaction is exothermic and is more likely to be spontaneous; positive ΔH values correspond to endothermic reactions. (Entropy also plays an important role in determining spontaneity, as some reactions with a positive enthalpy change are nevertheless spontaneous due to an entropy increase in the ...
The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Thermal decomposition is a chemical reaction where heat is a ...
Enthalpy change of solution for some selected compounds: hydrochloric acid-74.84 ammonium nitrate +25.69 ammonia-30.50 potassium hydroxide-57.61 caesium hydroxide-71.55 sodium chloride +3.87 potassium chlorate +41.38 acetic acid-1.51 sodium hydroxide-44.50 Change in enthalpy ΔH o in kJ/mol in water at 25°C [2]