CHM 1311 Final: CHM1311 Final Notes Part 4
2 Apr 2016
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Document Summary
The enthalpy change of an overall process is the sum of the enthalpy changes of its individual steps. We add known delta h values for the steps to get the unknown delta h. For a gas, the standard rate is 1 bar and ideal behavior. For a substance in aqueous solution, 1 mol/l concentration. Pure substance, most stable for of the substance at 1 bar and the temperature of interest. The standart state symbol shown as a degree sign indicates the variable has been measured with all substances in their standard states. Formation equations and their standard enthalpy changes. Standard enthalpy of formation is the enthalpy change for the formation equation when all substances are in their standard states. 1. for an element in standard state =0. Gasses have diffent different amounts of heat depending on state. Most compounds have a negative standart enthalpy of formation, most compounds have exothermic formations reactions. Standard enthalpies of reaction delta r h .
