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DesLee26
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__ 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
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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)
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The values of Keq tells us what?
the position of the equilibrium: whether the products or reactants are more stable, adn therefore energetically favored
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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)
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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
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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
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ΔG is a measure of what?
- the amount of energy available to do work
- = (free energy of products)-(free energy of reactants)
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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
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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
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The relationship between ΔGo and Keq is given by the expression?
Explain the values too.
Keq= e^(-ΔG o/RT)
- R= 8.314 J/ kelvin-mol
- T= absolute temp in K
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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
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In general, a reaction goes __ for values of ΔGo that are more negative than about -12 kJ/ mol.
nearly to completion
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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)
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At low temps, the __ usually much larger than the __, and the __ is sometimes ignored.
- enthalpy term (ΔHo)
- entropy
- entropy term
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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
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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.
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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.
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__ 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
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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
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The formation of strong bonds (the __) is usually the most important component in the driving force for a reaction.
change in enthalpy
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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
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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
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