Ethene, C2H4, can be produced in the following industrial system: C2H6 (g) + energy ↔ C2H4 (g) + H2 (g) what conditions are necessary to maximize the equilibrium yield of C2H4 are

Question

Select one:

a. 

high temperature and low pressure

b. 

low temperature and high pressure

c. 

high temperature and high pressure

d. 

low temperature and low pressure

Answer 1

C2H6 (g) + energy ↔ C2H4 (g) + H2 (g)

This equation tells us that energy is being used in the reactant side thus this equation is endothermic.

If this reaction is endothermic then if we increase the temperature it means we increase the heat of the reaction. thus the equilibrium is going to shift towards the product side ( which is what we want) because it wants to remove the excess heat.

From this, we can eliminate answers B and D.

Now we are left with A and C. low or high pressure.

1. If there is an increase in pressure then the equilibrium will shift towards the side of the reactions that have few moles of gas.
2. if there is a decrease in pressure then the equilibrium will shift towards the side of the reaction that has more moles of gas

C2H6 (g) + energy ↔ C2H4 (g) + H2 (g)

1 mole of C2H6 ↔ 1 mole of C2H4 and 1 mole of H2

reactant has 1 and product has 2 moles

thus we need to decrease the pressure so we can favor the product side.

The answer is A.