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60 Cards in this Set
- Front
- Back
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The First Law of Thermodynamics is also known as the... |
Law of Conservation of Energy. |
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In an process that involves an energy transaction,... |
a "heat tax" must be paid. |
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Thermodynamics allows predictions of which processes... |
will occur spontaneously. |
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A spontaneous process occurs without... |
ongoing outside intervention. |
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For mechanical systems, the direction of spontaneity is... |
towards lower potential energy. |
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For chemical systems, we need... |
analagous concept. |
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Note that spontaneous process is not equivalent to... |
a fast process. Thermodynamics and kinetics study different aspects of a chemical reaction.
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Non-spontaneous processes... |
can and do occur with outside assistance. |
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Examination of spontaneous endothermic processes leads to... |
the importance of increasing disorder in chemical processes. |
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Disorder or randomness is... |
the qualitative description of entropy. |
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entropy(S): a thermodynamic function that... |
increases with the number of energetically equivalent ways to arrange the components a system to achieve a particular state. |
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The most common units for entropy are |
J/K. |
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Entropy is a... |
state function, facilitating calculations of changes in entropy. |
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Entropy determines... |
the direction of physical and chemical change. |
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A macrostate is... |
what the system looks like from the outside; a micro-state is what the system looks like from the inside. |
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It is quite possible and common to have many different... |
micro-states that represent the same macrostate. |
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Systems tend towards the most... |
probable state which coincides with the state with greatest entropy. |
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The state with the highest... |
entropy is the one that disperses energy the most. |
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States with low energy concentration have... |
higher entropy than states with high energy concentration (as long as the amount of energy is constant between states). |
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The Second Law of Thermodynamics states... |
that for any spontaneous process, the entropy of the universe increases. |
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As a substance goes from solid to gas, its entropy... |
increases due to the number of ways it can "hold" energy. |
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Reactions resulting in an increase in the number of moles of gas... |
increase entropy. |
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Since the 2nd Law of Thermodynamics require that the entropy of the universes increases, it is... |
possible for the entropy of a system to decrease as long as the entropy of the surroundings increases enough to offset it. |
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If a system releases energy to the surroundings, the entropy... |
of the surroundings increases. |
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Entropy is temperature dependent. For a constant amount of energy dispersed,... |
DeltaS decreases as temperature increases.
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Gibbs Free Energy, (G), is formally defined as... |
G= H - TS |
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DeltaG can be used... |
to determine spontaneity using only information about the system. |
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If DeltaG is negative, the process is... |
spontaneous, if deltaG is positive, the process is non-spontaneous. |
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Since DeltaG involves DeltaH, DeltaS and T, different combinations of... |
enthalpy entropy and temperature determine the sign on DeltaG and hence the spontaneity. |
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The standard entropy change for a reaction, DeltaS^o of reaction, is.. |
the change in entropy for a process in which all reactants and products are in their standard states. |
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The Third Law of Thermodynamics states... |
that the entropy of a perfect crystal at absolute zero (0 K) is zero |
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The Third Law of Thermodynamics provides a reference point for... |
all other entropies. |
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Entropy increases as... |
substance goes from solid to liquid to gas. |
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The greater the molar mass,... |
the higher the entropy. |
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Less constrained allotropes have... |
more entropy than more constrained ones. |
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Complex compounds have... |
more entropy than simpler compounds. |
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Dissolved ionic solids have... |
more entropy than the undissolved solid. |
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Changes in standard entropies can... |
be calculated via a Hess's Law type of calculation. |
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DeltaG^o of reaction can be calculated by... |
separately calculating, the standard enthalpy change and the standard entropy change and using those values in the Gibbs free energy equation. |
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Just like a standard enthalpy of formation, there is a... |
standard free energy of formation (DeltaG^o of f). The standard free energy of formation is the change in free energy when 1 more of a compound forms from its constituent elements in their standard states. |
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Reactions with associated free energies can be... |
manipulated like thermochemical equations: 1. If an equation is multiplied by a factor, then the associated free energy change is multiplied by the same factor. 2. If an equation is reversed, then the free energy change switches sign; 3. If a series of reactions adds up to an overall reaction, the free energy change for the overall reaction is simply the sum of the free energy changes for each step. |
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Free energy is called "free" because... |
it is the energy that is theoretically available to do work. |
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The only way to get the theoretical maximum work from a chemical system is to... |
have the system change infinitesimally slowly such that the reaction is reversible. |
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Free energies can also be calculated.... |
under nonstandard conditions. |
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If there is no change in free energy, i.e. DeltaG = 0, then... |
the system is at equilibrium. |
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Equilibrium constants and changes in free energy are... |
intimately related. |
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Equilibrium constants are... |
temperature dependent. Data of K's obtained at different temperature can be used to find the standard enthalpy, standard entropy, and standard free energy changes for a system. |
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S = k ln W |
(Entrop equation) |
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DeltaS = S_final - S_initial |
(Change in entropy equation) |
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DeltaS_Universe > 0 |
(2nd law of Thermodynamics) |
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DeltaS_Universe = DeltaS_system + DeltaS_surroundings |
(Components of entropy of the universe) |
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DeltaS_Surroundings = (-DeltaH_System/T) |
(Equation to calculate entropy change of surroundings) |
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DeltaG = DeltaH_system - T DeltaS_system |
(Gibbs free energy equation) |
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G = H - TS |
(Definition of Gibbs free energy) |
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DeltaS^o_reaction = S^o_products - S^o_reactants |
(Standard entropy change for a reaction) |
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DeltaS^o_reaction = Sum of all moles_product * S^o(products) - Sum of all moles reactants * S^o (reactants) |
(Calculation of DeltaS^o_reaction) |
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DeltaG^o_reaction = Sum of all moles_product * G^o_f(products) - Sum of all moles reactants * G^o_f (reactants) |
(Hess's Law type calculation for DeltaG^o_reaction) |
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DeltaG_reaction =G^o_reaction + RT lnQ |
(Calculating nonstandard free energy) |
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DeltaG^o_reaction = -RT ln K |
(Relationship between DeltaG^o_reaction and K) |
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ln K = (-DeltaH^o_reaction/R) (1/T) + (DeltaS^o_reaction/R) |
(Relation between equilibrium constant and temperature) |
