CHEM10003 Lecture Notes - Lecture 18: Bond-Dissociation Energy, Molar Mass, Stoichiometry

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pinkgerbil486

27 Nov 2018

School

University of Melbourne

Department

Chemistry

Course

CHEM10003

Professor

Guy Jameson

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Document Summary

Open to environment so there is a constant pressure. The total enthalpy change for a chemical reaction is independent of the path by which the reaction occurs provided the starting and finishing states are the same for each reaction path. Corresponds to the standard enthalpy of reaction for the formation of one mole of ___ in its standard state (for co2 this is its gas phase) from its constituent elements in their standard state. The sum of all the standard enthalpy changes of formation of the products the sum of all the standard enthalpy changes of formation of the reactants. Heat released when a substance burns at constant pressure heat of combustion. The standard enthalpy change of combustion is the enthalpy change when 1 mol of a substance reacts completely with oxygen gas at 1 bar pressure. Hydrogen has a low molar mass, so there is a high energy per unit mass.

Related Questions

Calorimetry is a method used to measure changes inenthalpy, or heat, that occur during chemical processes. Two commoncalorimeters are constant-pressure calorimeters and constant-volume(or "bomb") calorimeters. Bomb calorimeters are used to measurecombustion and other gas-producing reactions, in which the reactionis observed in a strong, sealed vessel. A simple constant-pressurecalorimeter can be made from a foam coffee cup and a thermometer,in which energy changes in a reaction are observed via the changein temperature of the solution in the cup. The idea behindcalorimeters is that if they are sufficiently insulated from theoutside environment, any energy gained or lost in the chemicalreaction will be directly observable as a temperature and/orpressure change in the calorimeter.