Iodine/Thiosulfate Redox Titrations (OCR A-Level Chemistry A): Flashcards
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Purpose of iodine/thiosulfate titrations
Purpose of iodine/thiosulfate titrations
Determine concentration of oxidising agents
Product of thiosulfate oxidation
Product of thiosulfate oxidation
Tetrathionate,
Colour when iodine present
Colour when iodine present
Yellow-brown
When to add starch indicator
When to add starch indicator
At pale straw colour (near end point)
Colour after starch added to iodine
Colour after starch added to iodine
Deep blue-black
End point colour
End point colour
Colourless
Mole ratio ClO⁻ :
Mole ratio ClO⁻ :
1:2
Mole ratio Cu²⁺ :
Mole ratio Cu²⁺ :
1:1
Precipitate when Cu²⁺ reacts with I⁻
Precipitate when Cu²⁺ reacts with I⁻
White copper(I) iodide (CuI)
Why starch only near end
Why starch only near end
Complex may not break down if added too early