Iodine-thiosulfate Titration Flashcards
1
Q
Explain how iodine, a non-polar substance of very low water solubility, is brought into aqueous solution.
A
Reaction with I-, which forms tri-iodide which is water soluble
2
Q
What’s the indicator in an iodine experiment?
A
Starch
3
Q
When is the indicator added?
A
Near the end when it is a pale yellow colour
4
Q
What’s the colour change?
A
Brown->Straw->blue-black->colourless
5
Q
When they ask you to do a calculation involving iodine, do you use I or I2
A
I2
6
Q
Explain why the use of distilled water instead of deionised water throughout this experiment would be likely to ensure a more accurate result.
A
Distilled water is purer because in deionised water only ions have been removed
7
Q
What is a primary standard?
A
A Stable substance from which solutions of known conc. can be made
