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22 Cards in this Set
- Front
- Back
What is a reversible reaction
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A reaction which goes in both forward and backward directions
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What is equilibrium
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Reversible reaction in which the amount of each reactant/product remains constant
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Define dynamic
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Rate of forward reaction is equal to rate of backward reaction
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What is the position of equilibrium
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Measure of how far the reaction has proceeded to the right (products) or remained to the left (reactants)
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What does it mean if the position of equilibrium lies to the left
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Little product is formed (reactants predominate)
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What does it mean if the position of equilibrium lies to the right
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Little reactant remains (products predominate)
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What would happen to the position of equilibrium if concentration of reactants is increased
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Moves to the right
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What would happen to the position of equilibrium if concentration of products is increased
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Moves to the left
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What would happen to the position of equilibrium in an endothermic reaction if temperature is increased
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Moves to the right to oppose the change (higher product yield)
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What would happen to the position of equilibrium in an exothermic reaction if temperature is increased |
Moves to the left to oppose the change (lower product yield) |
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What would happen to the position of equilibrium if pressure is increased
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Moves to the side with fewer gas moles
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What action has the same effect as increasing pressure
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Decreasing volume
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Does the prescence of a catalyst effect the position of equilibrium
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No, but does allow equilibrium to be attained more quickly
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What are the expressions for a general reaction and its equilibrium constant
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for a reaction in the format
aA + bB ⇌ cC + dD Kc = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ |
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What are the units of the equilibrium constant
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Kc = (mol dm⁻³)⁽ᶜ⁺ᵈ⁾ / (mol dm⁻³)⁽ᵃ⁺ᵇ⁾
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What does the value of the equilibrium constant show
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Higher the value, further to the right position of equilibrium is
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What is the only thing to affect the equilibrium constant and how does it affect it
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Change in temperature
Increase in endo = moves position of equilibrium to the right and so equilibrium constant is higher Increase in exo = moves position of equilibrium to the left and so equilibrium constant is lower |
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What is the general rule when Kc > 1
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Generally more products than reactants and vice versa
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What are the 2 indutrial reaction examples of equilibrium
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- Ammonia produced from N and H in Haber process
- Conc sulfuric acid produced from sulfur dioxide and oxygen in Contact process |
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What is a compromise temperature
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Temp used as a compromise between achieving a reasonable yield and a fast enough rate of reaction
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Describe equilibrium in the Haber process
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N₂ + 3H₂ ⇌ 2NH₃ ΔH = -92.2kJ
Conditions: 450°C, 200atm, iron catalyst - Increase temp PoE moves left, lower yield - Increase pressure PoE moves right, higher yield - Iron catalyst makes equilibrium attained faster |
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Describe equilibrium in the Contact process
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2SO₂ + O₂ ⇌ 2SO₃ ΔH = -197kJ
Conditions: 450°C, 2atm, vanadium(v) oxide catalyst - Increase temp PoE moves left, lower yield - Increase pressure PoE moves right, higher yield - Vanadium catalyst makes equilibrium attained faster |