Test 3 Study Guide

Test 3 Study Guide - Chapter 6 Energy Relationships in...

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Chapter 6: Energy Relationships in Chemical Reactions Energy: the capacity to do work o Internal Energy of a System Kinetic Energy: the energy possessed by a moving object or motion of molecules. Potential Energy: energy that results from the position or configuration of a part of the system; energy available by virtue of the object’s position. Also, attractive and repulsive forces between electrons and nucleus. The partial + and – parts of molecules between molecules. o Thermal Energy: associated with motion of molecules ex. a coffee cup with 70°C and a bathtub of water at 40°C. The bathtub has more thermal energy because the volume is greater. o Radiant Energy: solar energy that comes from the sun o Chemical Energy: stored within the structural units of chemical substances Work: force * distance; directed energy change resulting from a process; w = PV or -PΔV (Boyle’s Law); work done by the system, w is negative ΔV > 0; work done to the system, w is positive ΔV < 0; it is not a state function, so it cannot be written as w = wf – wi because it * depends on how the process is carried out, or the path, and is not a property of the system, it manifests itself during a process or change. Heat: the transfer of thermal energy between two bodies that are at different temperatures; it is not a state function (see *). Thermochemistry / Thermodynamics: the study of heat change in chemical reactions or the study of interconversion of heat and other kinds of energy. System: what we’re interested in, a specific part of the universe o Open System: can exchange mass and energy, usually in the form of heat with its surroundings. ex. open flask o Closed System: allows the transfer of energy (heat) but not mass. ex. if a stopper is put on the flask o ex. transfer of energy from system to surroundings 2H2 (g) + O2 (g) 2 H2O (l) + energy A significant amount of energy is released. Endothermic process: energy from the surroundings going into the system or when the system gains energy from the surroundings. The energy of the products and energy of the reactants is equal to the heat supplied to the system by the surroundings. ex. boiling water Exothermic process: gives off heat or transfers energy to its surroundings. The energy of the products is less than the total energy of the reactants. The State of the System: the values of all relevant macroscopic properties. i.e. composition, energy, temperature, pressure, and volume. State Functions: properties that are determined by the state of the system regardless of how that condition was achieved; depend on initial and final states; independent of the path taken. Heat and work are not state functions because they are seen during a process and do not describe the state of the system.
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Laws of Thermodynamics o 1st Law of Thermodynamics: energy can be converted from one form to another, but cannot be created or destroyed ΔE system + ΔE surroundings = 0
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Test 3 Study Guide - Chapter 6 Energy Relationships in...

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