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The reaction between vanadium(IV) ions and manganate(VII) ions in acidic solution can be represented by the equation $$5V^{4+} + MnO_4^{-} + 8H^{+} \rightarrow 5V^{5+} + Mn^{2+} + 4H_2O$$ What volume, in dm³, of 0.020 mol dm⁻³ KMnO₄ is needed to oxidise 0.10 mol of vanadium(IV) ions completely? - AQA - A-Level Chemistry - Question 21 - 2022 - Paper 3

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The-reaction-between-vanadium(IV)-ions-and-manganate(VII)-ions-in-acidic-solution-can-be-represented-by-the-equation--$$5V^{4+}-+-MnO_4^{-}-+-8H^{+}-\rightarrow-5V^{5+}-+-Mn^{2+}-+-4H_2O$$--What-volume,-in-dm³,-of-0.020-mol-dm⁻³-KMnO₄-is-needed-to-oxidise-0.10-mol-of-vanadium(IV)-ions-completely?-AQA-A-Level Chemistry-Question 21-2022-Paper 3.png

The reaction between vanadium(IV) ions and manganate(VII) ions in acidic solution can be represented by the equation $$5V^{4+} + MnO_4^{-} + 8H^{+} \rightarrow 5V^{... show full transcript

Worked Solution & Example Answer:The reaction between vanadium(IV) ions and manganate(VII) ions in acidic solution can be represented by the equation $$5V^{4+} + MnO_4^{-} + 8H^{+} \rightarrow 5V^{5+} + Mn^{2+} + 4H_2O$$ What volume, in dm³, of 0.020 mol dm⁻³ KMnO₄ is needed to oxidise 0.10 mol of vanadium(IV) ions completely? - AQA - A-Level Chemistry - Question 21 - 2022 - Paper 3

Step 1

Calculate the moles of KMnO₄ needed to react with vanadium(IV)

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Answer

From the stoichiometry of the reaction, 1 mole of MnO₄⁻ reacts with 5 moles of V^{4+}. Therefore, for 0.10 moles of V^{4+}, the moles of KMnO₄ required are:

n=0.105=0.020 moles n = \frac{0.10}{5} = 0.020 \text{ moles }

Step 2

Use the concentration of KMnO₄ to find the volume required

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Answer

Using the formula:

extC=nV ext{C} = \frac{n}{V}

where C is the concentration (0.020 mol/dm³) and n is the number of moles (0.020 moles), we can rearrange the formula to find the volume (V):

V=nC=0.0200.020=1.0 dm³V = \frac{n}{C} = \frac{0.020}{0.020} = 1.0 \text{ dm³}

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