| Term | Definition |
|---|
| Spontaneous | occurs without outside intervention |
| Endothermic reactions are spontaneous at _______ temperatures. | high |
| Exothermic reactions are spontaneous at ______ temperatures. | low |
| entropy (s) | the change in entropy of the universe of a given process is a measure of the driving force behind that process |
| In spontaneous reactions there is an overall _______ in the entropy of the universe. | increase |
| Entropy is related to positional probability, which depends on the number of _____________ available | microstates |
| When two liquids are mixed, positional probability ___________. | increases |
| In an isothermal process the temperatures of the system and the surroundings are _________ and the change in energy equals________. | constant; zero |
| When no work is done and T is constant,this is called a ________ ___________. | free expansion |
| Work= integral from V1 to V2 of | P(ex) dV |
| External pressure is always almost exactly equal to | the pressure produced by the gas |
| w(rev)= | nRTln(v2/v1) = nRTln(P1/P2) |
| If there is no change in temperature, all heat is used to do _______. | work |
| q(rev)= | -w(rev) |
| Only when the _______ and the _________ are both done reversible (an _______ number of steps) is the universe the same after the cyclic process. | expansion, compression; infinite |
| In an irreversible process, more ______ must be put into the system than what the system produces. | work |
| All real processes are | irreversible |
| In a reversible process, both the ________ and the ___________ are returned exactly to their original conditions. | system, surroundings |
| Even if the system is cycled, in an irreversible process the __________ are changed in a permanent way. | surroundings |
| Entropy of one molecule (S)= | kB ln m (m = number of microstates corresponding to a given state) |
| m2/m1= | V2/V1 |
| ΔS= | R ln(V2/V1) |
| (q rev.)/T= | ΔS |
| change of ________ is reversible | state |
| at constant pressure ΔS= | nCp ln (T2/T1) |
| at constant volume ΔS= | nCv ln (T2/T1) |
| q rev. = | ΔH fusion |
| ΔS sys + ΔS surr = | ΔS univ |
| second law of thermodynamics | the entropy of the universe is increasing |
| If ΔS univ= 0, then the system is at | equilibrium |
| The entropy changes in the surroundings are primarily determined by ________ __________. | heat flow |
| ___________ is an important driving force for spontaneity | Exothemicity |
| ΔS surr = | -ΔH/T |
| Change in free energy (ΔG) = | ΔH - TΔS |
| At constant T and P, ΔS univ = | -ΔG/T |
| A process will only occur if the free energy __________. | decreases |
| At low temperatures ____ dominates and at high temperatures ______ dominates. | ΔH; ΔS |
| Fewer gaseous molecules mean fewer possible __________. | configurations |
| third law of thermodynamics | the entropy of a perfect crystal at 0 K is zeero |
| ΔS system= | sum of S products - sum of S reactants |
| Entropy is an ___________ property (depends on amount) | extensive |
| The more ________ the molecule, the higher the standard entropy value. | complex |
| Free energy is a _________ function. | state |
| Standard free energy of formation: | the change in free energy that accompanies the formation of 1 mole of that substance from its constituent elements with all reactants and products in their standard states |
| The standard free energy of formation of an element is | zero |
| At ____________, G=0 | equilibrium |
| ΔG = | ΔG* +RT ln(Q) (adjusting for non-standard conditions) |
| At equilibrium, ΔG*= | -RT ln(K) |
| ln (K)= | (-ΔH*/R=slope) (1/T) + (ΔS*/R=y-intercept) |
| van't Hoff equation: | ln (K2/K1) = (-ΔH*/R)(1/T2 - 1/T1) |
| As we use energy, we degrade its | usefulness |
| A gas expands to have more________. | entropy |
| Carnot cycles are the ________ expansion of a gas, giving maximum possible work.. | isothermal |
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