CHM135H1 Chapter Notes - Chapter 17: Standard Molar Entropy, Stoichiometry, Spontaneous Process
90
CHM135H1 Full Course Notes
Verified Note
90 documents
Document Summary
Thermodynamics: area that dealing with interconversion of heat, other forms of energy. Reverse nonspontaneous, takes place in presence of continuous external influence. Spontaneity depends on temperature, pressure, composition of reaction mixture. Nonspontaneous: qp < kp; spontaneous: qp > kp. Spontaneous reaction always moves reaction mixture towards equilibrium. Exothermic reactions: energy lost by system is heat gained by surroundings. Spontaneous changes not always exothermic: ice spontaneously absorbs heat, melts; liquid water absorbs heat, spontaneously boils; gaseous n2o4 absorbs heat when decomposes to no2; table salt absorbs heat when dissolves in water. Processes endothermic but spontaneous, system moves spontaneously to state of higher enthalpy by absorbing heat from surroundings. Enthalpy alone can"t account for direction of spontaneous change, second determinant is nature"s tendency to move to condition of maximum randomness. Entropy (s): molecular randomness, state function, s = sfinal - sinitial. When randomness of system increases, s > 0; when randomness decreases, s < 0.
