PPT-THERMOCHEMISTRY ENERGETICS/ENTHALPY

INTRODUCTION All reactions require energy to break bonds in the reactants and all reactions give off energy when new bonds form to make products The difference in energy required to break the bonds and to make the new bonds can tell you whether the reaction is endothermic or exothermic . is the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions. . Enthalpy Change of reaction . is the enthalpy change that accompanies a chemical reaction in molar quantities expressed in a chemical equation. . IB Topics 5 & 15. PART . 1: Heat and . Calorimetry. Above: thermit rxn. Energy: . a measure of the ability to do work.. Work: . to move an object against an opposing force.. Energy (J) = Force (N) x Distance (m). IB Topics 5 & 15. PART . 2: Calculating . . H via . Bond . Enthalpies & Hess’s Law. Above: thermit rxn. BOND ENTHALPIES. Enthalpy change (. . H) can also be calculated directly from bond enthalpies. Internal Energy Equation. ΔE = Q + W = Q . + . PΔV. If the reaction is carried out at a constant volume (ΔV = 0) , then ΔE = Q. If volume is constant, any heat added or removed changes the internal energy. Enthalpy. Enthalpy (H)is the total amount of energy contained within a substance. Included all forms of energy, kinetic, potential…. Very difficult to measure all forms of energy within a substance, therefore a change in enthalpies is measured whenever a change occurs.. Lecture 8 Topics. . Brown chapter 5. 8.1. :. . Kinetic . vs. potential energy. . 5.1. 8.2. :. . Transferring . energy as heat & work. Thermal energy. 8.3: . System . vs. surroundings. Lecture Presentation. © 20. 12. Pearson Education, Inc.. © 2012 Pearson Education, Inc.. Energy. Energy. is the ability to do work or transfer heat.. Energy used to cause an object that has mass to move is called . AP Chemistry. thermodynamics. : the study of energy and. its transformations. -- . thermochemistry. : the subdiscipline involving. chemical reactions and. energy changes . temperature.. . . Study of energy changes that occur during chemical reactions and changes of state. Endothermic. Process that absorbs/gains heat. Heat flows into the system (+q). Heat removed from the surroundings (-q). Why do chemical reactions happen?. Topic . 15: Energetics (. 8. . hours). 15.1 . Standard enthalpy changes of reaction. 15.1.1 . Define and apply the terms standard state, standard enthalpy change of formation (¬H ) f. Hago Energetics Enhancing power plants profits while reducing CO 2 emissions Hago Energetics Our mission is to reverse global warming Hago Energetics Our decreasing carbon budget Sources of GHG Emi A form of energy. Flows from warmer objects to cooler objects. Represented by the variable “q”. Measured by units: calorie or joule. 1 J = 0.2390 . cal. 4.184 J = 1 . cal. 1000 . cal. = 1 . kilocalorie . Define. . temperature. and state the units in which it . is measured.. Define. . heat. and state its units.. Perform. specific-heat calculations.. Solve. . problems involving enthalpies of reaction, enthalpies of formation, and enthalpies of combustion.. Change. First Law of Thermodynamics. Heat . (q. ). ,. work (. w. ) and internal energy (. E. ). Calculation of heat gained or lost by system. Calorimeter for measuring heat exchange (between system and surrounding;.