CHEM1061 1st Edition Lecture 14 Outline of Last Lecture I Stoichiometry with Gas Laws II Diffusion and Effusion III Thermochemistry IV Heat and Work V First Law of Thermodynamics Outline of Current Lecture VI Units of energy VII Enthalpy VIII Exothermic and Endothermic Processes IX Calorimetry X Specific Heat Capacity XI Molar Heat Capacity XII Calorimetry Current Lecture Units of Energy Si Unit of Energy Joule 1 J 1 kgxm 2 s 2 calorie cal amount of energy needed to raise temperature of 1 g of H2O by 1 degree Celsius 1 cal 4 184 J These 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 cal 1 Btu British thermal unit 1055 J Enthalpy Enthalpy H Change in enthalpy is delta H Heat is absorbed released at a constant pressure equals enthalpy q pressure delta H q pressure heat at constant pressure Exothermic and Endothermic Processes Delta 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 reaction a Heat goes in delta H 0 H products H reactants Calorimetry Measuring the heat of physical chemical changes is calorimetry Relative 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 Capacity Quantity 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 K q c x mass x change in T TABLE 6 2 values of C YOU DO NOT NEED TO MEMORIZE THESE FOR TEST When C is higher it takes more energy to raise T Molar Heat Capacity c q mol x change in T J mol x K Calorimetry Change in Energy universe Change in energy system Change in Energy surroundings 0 Change in E q w if only heat then change in E q Heat only q system q surroundings 0 q gain q loss 0
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