Reversibility and dynamic equilibria
3 marks · NormalSome students write the following equation:
Explain how you could tell whether this reaction is reversible or not, using the chemical symbols and the reaction itself.
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.
Show answer
The arrow (→) means the reaction is shown as irreversible, going only one way. For a reversible reaction, the equation must use ⇌ to show it can go both forward and backward. Without this symbol, it is not represented as reversible.
Also accept: No ⇌ symbol so not reversible; A reversible reaction would use ⇌ not →
Common mistakes: Ignoring the significance of the arrow symbol; Thinking all reactions are reversible regardless of the symbol
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States that the single arrow (→) means the reaction is irreversible
B2 · 1 mark · Explains that a reversible reaction uses the ⇌ symbol in chemical equations
B3 · 1 mark · Links the lack of ⇌ to the representation of reversibility (not shown as reversible)
Worked solution
The equation uses a single arrow (→), which means it only goes in one direction, so the reaction is not shown as reversible. A reversible reaction would use the double arrow (⇌), which means it can occur in both directions.