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Chemistry3
Cards for exam 3
Question | Answer |
---|---|
First Law of Thermodynamics | Energy is conserved |
Second law of Thermodynamics | Any system NOT at equilibrium has an inherent direction in which it will move in order to reach equilibrium *This is called a spontaneous reaction |
Third law of Thermodynamics | The Entropy of a pure crystalline solid is equal to zero at absolute zero (i.e. there is no disorder) |
Factors determining Spontaneity | 1) Exothermic reactions have a strong tendency to be spontaneous 2) The greater disorder of the system, the greater system entropy, therefore high spontaneity |
Gibbs free energy change(equation) | delta_g=delta_h-[(t(kelvin))(delta_s)] delta_g(rxn)=delta_g(prod)-delta_g(react) *State function |
Gibbs free energy change and reaction spontaneity | delta_g,negative= Occurs in forward direction delta_g,positive= Occurs in reverse direction delta_g,0= Equilibrium |
Standard Conditions | solids exist as pure solids liquids exist as pure liquids gases exist at 1 atm pressure solutions have all solutes present at a concentration of 1 mol/l 25 degrees Celsius |
Gibbs free energy change | Measure of the maximum amount of usable work that can be done by the system on the surroundings by a spontaneous process at constant pressure * Tells us nothing about the speed of the reaction |
Gibbs free energy change under non-standard conditions | delta_g=delta_g(std)-(R)(T)(ln(Q)) |
delta_g to K | delta_g=-(R)(T)(ln(K)) |