Chem 142 Unit 1 Latest Update Graded A+

Chem 142 Unit 1 Latest Update Graded A+ Thermodynamics The study of energy and its transformation Thermochemistry The study of chemical reactions and transformations and the energy changes that accompany these transformations Electrostatic Potential Energy Equation - k = constant - Q = the 2 charges (Eel is negative if the charges are opposite and positive if the charges are like) - d = distance between the two particles Potential Energy for like charges Repulsion; Positive; Closer together the more potential energy, farther apart the less potential energy Potential Energy for opposite charges Attraction; Negative; Closer together the less potential energy, father apart the more potential energy Electrostatic Attraction and Ions Electrostatic attraction holds ionic compounds together; ions close together = low potential energy; ions far apart = higher potential energy Dissociate Bonds Energy increases because energy is required to separate the atoms; energy is absorbed Create Bonds Energy decreases because energy is released when bonds are created First Law of Thermodynamics Energy can be converted from one form to another, but it is neither created nor destroyed Exothermic Reaction Graph (enthalpy vs time) Energy is released; change in H is negative Endothermic Reaction Graph (enthalpy vs time) Energy is absorbed; change in H is positive System The portion of the universe that we single out to study Surrounding Everything else with which the system can exchange energy Open System Part of the universe being studied that can exchange heat and mass with its surroundings Closed System Part of the universe being studied that can ONLY exchange heat with its surroundings (not mass) Isolated System Part of the universe that can NOT exchange heat or mass with its surroundings Internal Energy Sum of all kinetic and potential energies of all the components of a system (energy: E); We usually can't calculate all of the energies because it is too difficult to add up all of the different kinds, but we are concerned with