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Ethanedioic acid, H₂C₂O₄, can be oxidised by KMnO₄ in dilute sulfuric acid - CIE - A-Level Chemistry - Question 9 - 2019 - Paper 1
Question 9
Ethanedioic acid, H₂C₂O₄, can be oxidised by KMnO₄ in dilute sulfuric acid. The products of this reaction are carbon dioxide, water, potassium sulfate and manganese(... show full transcript
Worked Solution & Example Answer:Ethanedioic acid, H₂C₂O₄, can be oxidised by KMnO₄ in dilute sulfuric acid - CIE - A-Level Chemistry - Question 9 - 2019 - Paper 1
Step 1
How many water molecules are produced when five ethanedioic acid molecules are oxidised by KMnO₄ in dilute sulfuric acid?
Answer
To determine how many water molecules are produced, we first look at the given half-equation:
From this half-equation, we can see that when one molecule of ethanedioic acid (H₂C₂O₄) is oxidised, it produces 1 molecule of water in addition to the products mentioned. When the equation is balanced, we notice that each H⁺ produced leads to the formation of 1 water (H₂O) molecule when paired with an OH⁻ from the sulfuric acid.
Now, since 5 molecules of ethanedioic acid are being oxidised, the number of water molecules produced is:
total water produced = 5 molecules of H₂C₂O₄ × 1 water molecule per H₂C₂O₄ = 5 water molecules.
Thus, the total number of water molecules produced is 5. The answer is option A: 5.