C7.4 - Reversible Reactions

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What is a reversible reaction?
A reaction in which the products can be turned back into the reactants.
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How is this shown?
A double ended arrow symbol.
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What happens when reversible reactions form a state of equilibrum?
They do not stop, but the forwards and backwards reactions happen at the same rate.
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What is the haber process?
A non biological way of fixing nitrogen to produce ammonia.
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Are the feedstocks used in the haber process renewables?
Yes; nitrogen and hydrogen come from the air and natural gases.
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Do the reactants of the haber process reach equilibrum?
No; they do not stay in the reactor long enough.
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What is the symbol equation for this process?
2H2 + N3 = 2NH3
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How is the yield of ammonia increased?
Unused hydrogen and nitrogen is recycled, so that there are no waste products.
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Why does the temperature have to be compromised?
Increasing the temperature increases the backwards reaction rate, because it is endothermic. However, too much of a decrease will make the reaction too slow. The compromise temperature is 450 degrees celsius.
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Why does the pressure have to be compromised?
A high pressure increases the forwards reaction rate, because there are more product molecules than reactants. However, increasing it too much is dangerous and expensive; as a result, 200 atmospheres of pressure are used.
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What type of catalyst is used in the Haber process?
An iron catalyst.
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Some organisms can fix nitrogen at room temperature and pressure. Why is this relevant to chemists?
Because, if they can mimic the enzymes of these organisms, they can be used in the Haber process to decrease the amount of pressure and heat required.
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Finally, why is ammonia important?
It is a fertiliser; meaning that it increases the crop yield, and consequently farming profits.
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What else does ammonia make?
Plastics, explosives and pharmaceuticals.
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What is the downside to using ammonia as a fertiliser?
Eutrophication.
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Other cards in this set

Card 2

Front

How is this shown?

Back

A double ended arrow symbol.

Card 3

Front

What happens when reversible reactions form a state of equilibrum?

Back

Preview of the front of card 3

Card 4

Front

What is the haber process?

Back

Preview of the front of card 4

Card 5

Front

Are the feedstocks used in the haber process renewables?

Back

Preview of the front of card 5
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