Term
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Definition
A system where the following opposite reactions are taking place:
reactant becoming product
product becoming reactant |
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Term
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Definition
| The point in a reversible reaction where the forward and reverse reactions are taking place at the same rate. |
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Term
| Are concentrations of product and reactant equal at equilibrium? |
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Definition
| No. They are constant but not equal. Their relative concentrations are determined by the value of the equilibrium constant at that temperature. |
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Term
Write the equilibrium expression:
aA + bB ↔ cC + dD |
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Definition
Keq = [C]c[D]d/[A]a[B]b
Keq = equilibrium constant |
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Term
| Haw are reactant and product concentrations related to the magnitude of Keq? |
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Definition
If Keq is large
[reactant] is small and [product ] is large.
If Keq is small
[reactant] is large and [product] is small. |
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Term
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Definition
| If stress is placed on a system at equilibrium, equilibrium shifts in order to counteract the effects of stress and regain equilibrium. |
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Term
| How does a concentration change affect equilibrium? |
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Definition
| If one of the substances is added or removed, all concentrations of substances adjust to a new equilibrium with the same Keq. |
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Term
| How does a change in temperature affect equilibrium? |
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Definition
| The reaction shifts to a new equilibrium point with a new Keq. If the temperature is raised, the equilibrium is shifted to reaction which absorbs heat. |
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Term
| How does a pressure change affect equilibrium? |
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Definition
| (Only in reactions where gases are involved.) The reaction will shift to oppose the pressure change, resulting in fewer moles of gas particles. |
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Term
Ionization Constant
Write the expression for ionization of acid: HA |
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Definition
For substances in solution that partially ionize, an equilibrium expression may be written with Ki.
Ki = [H+][A-]/[HA] |
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Term
| What are the two driving forces which control reactions? |
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Definition
A drive toward increased entropy (disorder).
A drive toward decreased enthalpy (lower heat content). |
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Term
| Second Law of Thermodynamics |
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Definition
| The entropy of the universe increases for any spontaneous process. |
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Term
| List three processes where entropy increases. |
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Definition
A gas if formed from a solid or liquid.
A gas is evolved from a solution.
Crystals dissolve in water. |
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Term
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Definition
| A property which reflects a system's capacity to do useful work. |
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Term
| Write the free energy equation. |
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Definition
ΔG = ΔH - TΔS
G = free energy
S = entropy
H = enthalpy
T = Kelvin |
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Term
| How can ΔG be used to predict if a reaction is spontaneous? |
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Definition
ΔG
positive: not spontaneous
negative: spontaneous
equals 0: at equilibrium |
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