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In which one of the following would the position of the equilibrium not be affected by a volume change at constant temperature? A - VCE - SSCE Chemistry - Question 3 - 2002 - Paper 1
Question 3
In which one of the following would the position of the equilibrium not be affected by a volume change at constant temperature? A. 2CO(g) + O2(g) ⇌ 2CO2(g) B. C2H4(g... show full transcript
Worked Solution & Example Answer:In which one of the following would the position of the equilibrium not be affected by a volume change at constant temperature? A - VCE - SSCE Chemistry - Question 3 - 2002 - Paper 1
Step 1
B. C2H4(g) ⇌ C2H6(g) + H2(g)
Answer
The position of equilibrium in a reaction is influenced by changes in volume when there is a difference in the number of gas molecules between the reactants and products. In this case:
- Reactants: 1 mole of C2H4(g)
- Products: 1 mole of C2H6(g) + 1 mole of H2(g) = 2 moles
Since there are more moles of gas on the product side than on the reactant side, a decrease in volume will shift the equilibrium to the left to favor the reactants in order to reduce the pressure. Thus, this equilibrium would be affected by a volume change.
To determine which reaction is unaffected by volume change, we need to look for a reaction where moles of gas on both sides are equal.
- In contrast, choices A, C, and D all show a clear imbalance in mole count that would respond to volume changes. Thus, option B indicates a reaction that would be affected and is not the correct answer. The case of equilibria being unaffected must yield an equal number of moles on both sides, which corresponds clearly in the choosing process.