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. (Extended Tier Only)
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. (Extended Tier Only)
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. (Extended Tier Only)
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. (Extended Tier Only)
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? (Extended Tier Only)
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? (Extended Tier Only)
The rate of the backward reaction will increase until the system reaches dynamic equilibrium.
True of False?
Catalysts do not change the position of equilibrium. (Extended Tier Only)
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. (Extended Tier Only)
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. (Extended Tier Only)
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
(Extended Tier Only)
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? (Extended Tier Only)
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. (Extended Tier Only)
False.
An endothermic reaction is represented by a positive enthalpy change.