Reversible Reactions and Equilibria
5 marks · EasyReversible reactions often behave differently in sealed containers. Use your knowledge to answer the following questions.
State one example of a reversible reaction and write its equation using the proper symbol.
Explain why it is important for a container to be sealed when studying the equilibrium of a reversible reaction.
Describe, with reference to sealed containers, how the forward and reverse reactions compare at dynamic equilibrium.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) CuSO4·5H2O(s) \rightleftharpoons CuSO4(s) + 5H2O(l) or NH4Cl(s) \rightleftharpoons NH3(g) + HCl(g) · must show Correct equation with reversible arrow, Name of the correct reaction
(b) — · must show A sealed container prevents loss or gain of substances
(c) — · must show At dynamic equilibrium in a sealed container, forward and reverse reactions occur at equal rate
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Names a valid reversible reaction (e.g., copper(II) sulfate dehydration or ammonium chloride decomposition)
B2 (a) · 1 mark · Gives balanced equation using reversible arrow and correct state symbols
B3 (b) · 1 mark · States that a sealed container prevents substances entering or leaving
B4 (b) · 1 mark · Links sealed container to reliable achievement of equilibrium
B5 (c) · 1 mark · States forward and reverse rates are equal at equilibrium
Worked solution
a) Example: The dehydration of hydrated copper(II) sulfate. Equation: CuSO4·5H2O(s) \rightleftharpoons CuSO4(s) + 5H2O(l)
b) In a sealed container, no substances can enter or leave, so an accurate equilibrium can establish between reactants and products.
c) The forward and reverse reactions occur at exactly the same rate when equilibrium is reached in a sealed container.