If a reversible reaction is exothermic in one direction...
... it is endothermic in the opposite direction. The same amount of energy is transferred
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If the reactants and products are in a closed system..
... they can be in a state of dynamic equilibrium
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What happens in a dynamic equilibrium?
the rate of the forward reaction is equal to the rate of the backward reaction. The amounts of the reactants and products remain the same.
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What if there are more products than reactants?
The equilibrium lies to the left
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What determines the reaction's position?
the conditions
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What is Le Chatelier's Principle?
It states that if a dynamic equilbrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change
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if the the temperatures is lowered?
the yield from the endothermic reaction increases and the yield from the exothemric reaction decreases. This acts to decrease the temperatures and counteract the change
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if the pressure/concentration increases?
the reaction that produces the lower number of molecules is favoured. this will decrease the pressure and counteract the original change.
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What do catalysts do?
they do not change the position of the equilibrium, they increase the rate of both reactions.
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Name one process that uses Le Chatelier's Principle to its advantage
the Haber process which is used to manufacture ammonia
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What raw materials are used to make ammonia and how do you obtain them?
nitrogen - obtained from the air, hydrogen - natural gas with steam.
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Describe the Haber process
the gases are passed over a catalyst of iron at a temperature of 450degrees and a pressure of 200 atmospheres. They react to make ammonia which is liquified and removed and the remaining nitrogen and hydrogen is recycled
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WHat is the reaction's symbol equation?
N2 (g) + (3)H2 (g) >< (2)NH3 (g)
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What are the ideal conditions of a high yield of ammonia?
high pressure - more molecules on the left, low temperature - forward reaction is exothermic
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Why are the conditions like they are?
pressure not too high - expensive, temp not too low - too slow
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How can ammonia be used?
it dissolves in water to make an alkaline solution. it can reacted with nitric acid to make ammonium nitrate which is a fertiliser
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Other cards in this set
Card 2
Front
If a reversible reaction is exothermic in one direction...
Back
... it is endothermic in the opposite direction. The same amount of energy is transferred
Card 3
Front
If the reactants and products are in a closed system..
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