Define the term reversible reaction.
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Define the term reversible reaction.
A reversible reaction is a reaction that can occur in both directions: the forward reaction (which forms the products) and the reverse direction (which forms the reactants).
How are reversible reactions represented in chemical equations?
Reversible reactions are represented using two opposing arrows, ⇌.
When ammonium chloride is heated, what are the products of the reaction?
When ammonium chloride is heated, ammonia and hydrogen chloride are formed.
State what is observed when hydrated copper sulfate is heated.
When hydrated copper sulfate is heated the colour change is blue to white and colourless liquid (water) collects at the top of the test tube.
What is an anhydrous salt?
Anhydrous salts are those that have lost their water of crystallisation.
State the equation for the reversible reaction when hydrated copper(II) sulfate, CuSO4.5H2O, is heated.
The equation for the reversible reaction when copper(II) sulfate is heated is:
CuSO4.5H2O ⇌ CuSO4 + 5H2O
If the forward reaction of a reversible reaction is exothermic, what is the energy change of the reverse reaction?
If the forward reaction of a reversible reaction is exothermic, the reverse reaction is endothermic.
Define the term dynamic equilibrium.
Dynamic equilibrium is where the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant.
Define the term closed system.
A closed system is a system where none of the reactants or products can enter or leave the reaction vessel.
Define the term open system.
An open system is a system where the reactants or products can both enter or leave the reaction vessel.
True or False?
Equilibrium can only be reached in a closed system.
True.
Dynamic equilibrium can only occur in a closed system as none of the reactants or products are able to leave the reaction vessel.
In a reversible reaction, when is the concentration of the reactants the highest?
In a reversible reaction, the concentration of the reactants is highest at the start of the reaction.
How does the rate of the reverse reaction change during a reversible reaction?
The rate of the reverse reaction will increase until the system reaches dynamic equilibrium.
What is the Haber Process?
The Haber Process is the industrial process for manufacturing ammonia from nitrogen and hydrogen gases.
What is the equation for the reversible reaction in the Haber Process?
The equation for the Haber Process is:
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
What catalyst is used in the Haber Process?
The catalyst used in the Haber Process is iron.
True or False?
Increasing the temperature of the Haber Process will produce a high yield of ammonia.
N2 (g) + 3H2 (g) ⇌ 2NH3 (g) ΔH=−92.4 kJ/mol
False.
Decreasing the temperature of the Haber Process will produce a high yield of ammonia. This is because the forward reaction is exothermic (ΔH=−92.4 kJ/mol)
State the meaning of compromise conditions.
Compromise conditions are the conditions chosen to give a good balance between product yield, reaction rate and production cost, rather than ideal conditions for any one factor.
True or False?
Increasing the pressure of the Haber Process will produce a high yield of ammonia.
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
True.
Increasing the pressure of the Haber Process will produce a high yield of ammonia. This is because there are more gaseous molecules on the left hand side.
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
What is the compromise temperature used in the Haber Process?
The compromise temperature used is 450 °C.
What is the compromise pressure used in the Haber Process?
The compromise pressure used is 200 atm.
Why is a compromise temperature used in the Haber Process?
A compromise temperature is used to balance having a lower yield of products but being made more quickly.
Why is a compromise pressure used in the Haber Process?
A compromise pressure is used to balance a lower yield of products being made safely and economically.
How is ammonia removed from the reaction vessel?
Ammonia is removed from the reaction vessel by being cooled and liquified.
What happens to unreacted nitrogen and hydrogen gas in the Haber process?
The unreacted hydrogen and nitrogen gases are recycled back into the system and start over again
Where are hydrogen and nitrogen gas obtained from to be used in the Haber Process?
Hydrogen is obtained from natural gas and nitrogen is obtained from the air.
True of False?
Catalysts do not change the position of equilibrium.
True.
Catalysts do not change the position of equilibrium.
True or False?
A catalysts only speeds up the rate of the forward reaction in a reversible reaction.
False.
A catalyst speeds up the rate of both the forward and backward reactions.
True or False?
If the forward reaction is exothermic, the backward reaction is favoured by increasing the temperature.
False.
If the forward reaction is exothermic, the backward reaction is favoured by decreasing the temperature
In the following system, would an increase or decrease in pressure favour the forward reaction?
2A + 2B ⇌ C + D
Increasing the pressure would favour the forward reaction.
This is because there are 4 molecules on the left and side and 2 molecules on the right hand side.
An increase in pressure will favour the side with the fewest number of molecules.
If the forward reaction is endothermic, would a high or low temperature increase the yield of products?
If the forward reaction is endothermic, a high temperature would increase the yield of products.
This is because the forward reaction is endothermic. A high temperature would favour the endothermic pathway to oppose the increase.
True of False?
An endothermic reaction is represented by the negative enthalpy change.
False.
An endothermic reaction is represented by a positive enthalpy change.
True or False?
Increasing pressure shifts the equilibrium to favour the side with more gas molecules.
False.
Increasing pressure shifts the equilibrium to favour the side with fewer gas molecules.
What is the effect of decreasing the concentration of a product?
Decreasing the concentration of a product shifts the equilibrium to the left, favouring the reactants.
If the concentration of a reactant decreases, how does the equilibrium shift?
Equilibrium shifts to the left to reduce the effect of a decrease in reactant (or an increase in the concentration of product).
If the pressure decreases, how does the equilibrium of a reaction shift?
Equilibrium shifts in the direction that produces the larger number of molecules of gas to increase the pressure again.