Orgo Ch 4.4-4.6

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Orgo Ch 4.4-4.6
2013-09-30 22:21:45
CHM 201

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  1. __ is the branch of chem that deals with the energy changes accompanying chemical and physical transformations. These energy changes are most useful for describing the properties of systems at __.
    • thermodynamics
    • equilibrium
  2. The equilibrium concentrations of reactants and products are governed by the __ of the reaction. 
    How is the equation set up?
    • equilibrium constant
    • concentration of products/ concentration of reactants (the moles would be the powers)
  3. The values of Keq tells us what?
    the position of the equilibrium: whether the products or reactants are more stable, adn therefore energetically favored
  4. If Keq is larger than one, what? less than one?
    • the reaction is favored as written from left to right
    • the reverse reaction is favored (from right to left as written)
  5. When the Keq is extremely large, what? The value of Keq is a measure of what?
    • the reaction is said to go to completion
    • the reaction's tendency to go to completion
  6. From the value of Keq we can calculate the change in __ (sometimes called __) that accompanies the reaction. __ is represented by __ and the change (__) in free energy is associated with a reaction represented by __, the difference between the free energy of the products and the free energy of the reactants.
    • free energy
    • Gibbs free energy
    • free energy
    • G
    • Δ
    • ΔG
  7. ΔG is a measure of what?
    • the amount of energy available to do work
    • = (free energy of products)-(free energy of reactants)
  8. If the energy levels of the products are lower than the energy levels of the reactants, then what?
    the reaction is energetically favored; and this equation gives a negative value of ΔG, corresponding to a decrease in the energy of the system
  9. The __ is most commonly used. The symbol o designates __.
    • standard Gibbs free energy change (ΔGo)
    • a reaction involving reactants and products in their standard state
  10. The relationship between ΔGo and Keq is given by the expression?
    Explain the values too.
    Keq= e^(-ΔGo/RT)

    • R= 8.314 J/ kelvin-mol
    • T= absolute temp in K
  11. The formula shows that a reaction is favored if what? 
    A reaction that has a __ is what?
    These predictions agree with our intuition that reactions should go from __ to __ with a net __ in __
    • it has a negative value
    • positive value of ΔGo
    • unfavorable
    • higher-energy states
    • lower-energy states
    • decrease
    • free energy
  12. In general, a reaction goes __ for values of ΔGo that are more negative than about -12 kJ/ mol.
    nearly to completion
  13. Two factors contribute to the change in free energy:
    • the change in enthalpy and the change in entropy multipled by the temperature
    • ΔGo= ΔHo-TΔS
    • ΔGo= (free energy of products)-(free energy of reactants)
    • ΔHo= (enthalpy of products)-(enthalpy of reactants)
    • ΔSo= (entropy of products)-(entropy of reactants)
  14. At low temps, the __ usually much larger than the __, and the __ is sometimes ignored.
    • enthalpy term (ΔHo)
    • entropy 
    • entropy term
  15. The __ is the heat of reaction-- the amount of heat evolved or consumed in the course of a reaction, usually given in kj per mole. The __ is a measure of the relative __ in the products and reactants. Reactions tend to favor products with the __ (those with the __).
    • change in enthalpy
    • enthalpy change
    • strength of bonding
    • lowest enthalpy
    • strongest bonds
  16. If weaker bonds are broken and stronger bonds are formed, heat is evolved and the reaction is __. In an __ reaction, the __ term makes a favorable negative contribution to ΔGo.
    • exothermic x2
    • enthalpy
  17. If stronger bonds are broken and weaker bonds are formed, then energy is consumed in the reaction, and the reaction is __. In an __ reaction, the __ term makes an unfavorable positive contribution to ΔGo.
    • endothermic x2
    • enthalpy
  18. __ is often described as randomness, disorder, or freedom of motion. Reactions tend to favor products with the __.A __ value of the __ change (ΔSo), indicating that the products have more freedom of motion than the reactions, makes a favorable (negative) contribution to ΔGo.
    • entropy 
    • greatest entropy
    • positive
    • entropy change
  19. In many cases, the __ is much larger than the __, and the __ term dominates the equation for ΔGo. Thus, a __ value of ΔSo does not necessarily mean that the reaction has an __ value of ΔGo.
    • enthalpy change
    • entropy change
    • enthalpy term
    • negative
    • unfavorable
  20. The formation of strong bonds (the __) is usually the most important component in the driving force for a reaction.
    change in enthalpy
  21. The __ is the largest factor in the driving force for chlorination. This is the case in most organic reactions: The __ term is often small in relation to the __ term.
    • enthalpy change
    • entropy
    • enthalpy
  22. When discussing chemical reactions involving breaking and forming of bonds, we can use the values of the __, under the assumption that ΔGo=ΔHo. However, this may not always be the case because some may have larger changes in entropy and small changes in enthalpy.
    enthalpy changes