CAIE A-Level Chemistry 24.2.6 From E

Practise comparing E° values to decide which species act as stronger oxidising or reducing agents under standard conditions.

Exam points

explain non-reaction by placing an E° value between relevant oxidant and reductant couples

[Maximum number: 2]

Some electrode potentials are shown in Table 3.1.

Table 3.1

(a)

The vanadium-containing species in the electrode reactions given in Table 3.1 are $\mathrm{V}, \mathrm{V}^{2+}$ , $\mathrm{V}^{3+}, \mathrm{VO}^{2+}$ and $\mathrm{VO}_{2}{ }^{+}$ .

[ 2 ]

(i)

Identify one vanadium-containing species that does not react with $\mathrm{Fe}^{2+}$ ions under standard conditions.

Use data from Table 3.1 to explain your answer.

[ 1 ]

(for specified $\mathrm{V}^{2+}, \mathrm{V}^{3+}$ or $\mathrm{VO}^{2+}$ ) $\mathrm{E}^{\ominus}$ is more positive than / above -0.44 AND more negative than / below 0.77 V [1]

(ii)

Identify all the vanadium-containing species that will react with $\mathrm{Fe}^{2+}$ ions under standard conditions.

[ 1 ]

V and $\mathrm{VO}_{2}{ }^{+}$ [1]

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24.2.6—From E question 1

Question (a)

Question (i)

Question (ii)