University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2022
Views:

476

Pages:

1
Author:

gewoekerdodx

Unit 6: Thermodynamics Endothermic and Exothermic Processes ● Endothermic: substance absorbs energy from the surroundings, causing vessel to become colder ● Exothermic: substance releases energy into its surroundings, causing vessel to become warmer Energy Diagrams Heat Capacity and Calorimetry ● q = mcΔT  ● q = heat, m = mass, C = specific heat, ΔT = change in temperature ● Heat capacity is the energy needed to raise the temperature by one degree J/K or J/C (specific = raise one gram of substance) ● 1st law of thermodynamics = conservation of energy Enthalpy of Reaction ● Enthalpy change represents amount of heat released/absorbed at constant pressure ● Bond energy/bond enthalpy are interchangeable Bond Enthalpies ● The average energy required to break all of the bonds in the reactant molecules can be estimated by adding up the average bond energies of all the bonds in the reactant molecules. Likewise, the average energy released in forming the bonds in the product molecules can be estimated. If the energy released is greater than the energy required, the reaction is exothermic. If the energy required is greater than the energy released, the reaction is endothermic. Enthalpy of Formation ● Enthalpy of Formation (ΔHf): enthalpy change for the formation of 1 mol of a compound from its component elements ● Hess’s Law: states that if a reaction can be described as a series of steps, then ΔH for the overall reaction is simply the sum of the ΔH values for all the steps