Heat/Temperature & Systems 330_06_04 Energy: Enthalpy of Chemical Reactions

Terms & Concepts Heat: the transfer of thermal energy between two bodies that are at different temperatures. thermochemistry = the study of heat change in in chemical reactions measured as “heat flow”  temperature the property of matter which reflects the quantity of energy of motion of the component particles. Heat versus Temperature: The water in the bathtub may have more heat, but the water in the cup is hotter.

Enthalpy of Chemical Reactions Chemical reactions involving heat: 2H2(g) + O2(g)  2H2O(l) + energy State symbols are very important in thermochemistry. Identify the parts: The reacting mixture (H2,O2, & H2O molecules), system (open, closed, isolated), and surroundings (the rest of the universe)

Two Types of Processes exothermic reaction transfers heat from the system to the surroundings. 2H2(g) + O2(g)  2H2O(l) + energy endothermic reaction transfers heat from the surroundings to the system. H2O(l) + energy  H2O(g) 330_06_02 Energy: Chemical Reactions

Terms & Concepts Thermochemistry: The study of heat change in chemical reactions System: the specific part of the universe that is of interest in the study allows the transfer of energy (heat) and mass allows the transfer of energy (heat) but not mass does not allow energy or mass transfer open closed isolated

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