Photo AI
This question is about vanadium compounds and ions - AQA - A-Level Chemistry - Question 9 - 2018 - Paper 1
Question 9
This question is about vanadium compounds and ions. Use data from Table 4 to identify the species that can be used to reduce VO₄²⁻ ions to VO₃⁻ in aqueous solution a... show full transcript
Worked Solution & Example Answer:This question is about vanadium compounds and ions - AQA - A-Level Chemistry - Question 9 - 2018 - Paper 1
Step 1
Identify the suitable reducing agent
Answer
From Table 4, VO₄²⁻ can be reduced to VO₃⁻, which has a standard electrode potential (E°) of +1.00 V. The species capable of reducing VO₄²⁻ should have a higher E° value. Considering the listed species, Cl₂ has an E° of +1.36 V, making it the best candidate for the reduction.
Step 2
Explain why the chosen species can reduce VO₄²⁻
Answer
The reaction favorability can be assessed using the standard electrode potentials. A species with a more positive E° value indicates a greater tendency to gain electrons, thus functioning as a stronger oxidizing agent. Cl₂, with E° = +1.36 V, can effectively reduce VO₄²⁻ to VO₃⁻ as it exceeds the potential of the VO₄²⁻/VO₃⁻ couple.