CHEM1061 1st Edition Lecture 14Outline of Last Lecture I. Stoichiometry with Gas LawsII. Diffusion and EffusionIII. ThermochemistryIV. Heat and WorkV. First Law of ThermodynamicsOutline of Current Lecture VI. Units of energy VII. EnthalpyVIII. Exothermic and Endothermic ProcessesIX. CalorimetryX. Specific Heat CapacityXI. Molar Heat CapacityXII. CalorimetryCurrent LectureUnits of EnergySi Unit of Energy: Joule = 1 J = 1 kgxm^2/s^2calorie= (cal) = amount of energy needed to raise temperature of 1 g of H2O by 1 degree Celsius. 1 cal = 4.184 JThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1 Cal = (nutritional Calorie) = 1 kilocal = 1000 cal1 Btu = British thermal unit = 1055 JEnthalpyEnthalpy = HChange in enthalpy is delta HHeat is absorbed/released at a constant pressure equals enthalpyq(pressure) = delta Hq(pressure) = heat at constant pressureExothermic and Endothermic ProcessesDelta H = H(final) – H(initial) = H(products) – H(reactants)1) Exothermic reaction a. Heat goes out (delta H < 0) H(products) < H(reactants)2) Endothermic reactiona. Heat goes in (delta H > 0) H(products > H(reactants)CalorimetryMeasuring the heat of physical/chemical changes is calorimetryRelative energy change to heat realeased/absorbed by looking at change in T.Q is proportional to T q= constant x change in T constant is heat capacity.Heat capacity: quantity of heat required to change temperature by 1 kelvin (1K)Specific Heat CapacityQuantity of heat required to change temperature of 1 g of an object by 1 Specific heat capacity = c = q/ mass x change in T = J/g x Kq = c x mass x change in TTABLE 6.2 values of C (YOU DO NOT NEED TO MEMORIZE THESE FOR TEST) When C is higher, it takes more energy to raise TMolar Heat Capacityc = q/mol x change in T = J/mol x KCalorimetryChange in Energy (universe) = Change in energy (system) + Change in Energy (surroundings) =0Change in E = q + w if only heat then change in E = qHeat only q(system) + q(surroundings) = 0 q(gain) + q(loss) =
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