Term
1. Reversible reaction
2. Equilibrium |
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Definition
1. A system where the following opposite reactions are taking place: reactant becoming product; product becoming reactant
2. The point in a reversible reaction where the foward 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 by the value of the equlibrium constant at that temperature. |
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Term
Write the equilibrium expressions for:
aA + bB ↔ cC + dD |
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Definition
Keq = [C]c[D]d/[A]a[B]b
Keq = equlibrium constant |
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Term
| How 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
1. Le Chatelier's Principle
2. How does a concentration change affect equilibrium? |
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Definition
1. If stress is placed on a system at equilibrium, the equilibrium shifts in order the counteract the effects of the stress and regain equilibrium
2. If one of the substances is added or removed, all the concentrations of substances adjust to a new equilibrium with the same Keq |
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Term
1. How does a change in temperature affect equilibrium?
2. How does a pressure change affect equilibrium? |
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Definition
1. 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
2. Only in reactions where gases are involved. The reaction will shift to oppose pressure change, resulting in fewer moles of gas particles |
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Term
Ionization Constant
Write the expression for the 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
1. What are the two driving forces that control reactions?
2. Second Law of Thermodynamics |
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Definition
1. A drive towards increased entropy (disorder). A drive towards decrease enthalpy (lower heat content)
2. 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 is formed from a solid or liquid
A gas is evolved from solution
Crystals dissolve in water |
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Term
Free Energy Change (ΔG)
Write the free energy equation |
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Definition
A property which reflects a system's capacity to do useful work
ΔG = ΔH - TΔS
G=free energy
H=enthalpy
S=entropy
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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