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A student observed the reactions when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid - CIE - A-Level Chemistry - Question 17 - 2015 - Paper 1
Question 17
A student observed the reactions when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric... show full transcript
Worked Solution & Example Answer:A student observed the reactions when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid - CIE - A-Level Chemistry - Question 17 - 2015 - Paper 1
Step 1
Which deduction can be made from these observations?
Answer
To analyze the observations, we focus on the products formed when sodium chloride and sodium iodide react with concentrated sulfuric acid and concentrated phosphoric acid.
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Sodium Chloride Reaction: When sodium chloride reacts with concentrated sulfuric acid, a colourless acidic gas is formed. This indicates that sulfuric acid is acting as an acid and possibly a weak oxidizing agent in this case.
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Sodium Iodide Reaction: In contrast, the reaction with sodium iodide produced purple vapour with concentrated sulfuric acid, indicating that iodine gas is being released, showing the oxidizing power of sulfuric acid.
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Both Reactions with Phosphoric Acid: The phosphoric acid reactions produced colourless acidic gases in both cases, showing that it does not have the same oxidizing properties as concentrated sulfuric acid.
Considering option D, the observation indicates that concentrated sulfuric acid is indeed a stronger oxidizing agent than iodine as it can oxidize iodide ions (I⁻) to iodine (I₂).
Thus, the correct deduction is that D) Concentrated sulfuric acid is a stronger oxidising agent than iodine.