Which of the following is not coloured?

Options

A. `I_(2)O_(6)`
B. `I_(2)O_(4)`
C. `I_(4)O_(9)`
D. All of these

Answer

1

Explanation

Iodine pentoxide `(I_(2)O_(5))` forms stable white hygroscopic crystals. It is formed by heating iodic acid `(HIO_(3))` at `170^(@)C`. It react with `CO` to yield `CO_(2)` and `I_(2)` . It has the following structure:

The soild is a three-dimensional network, with strong intermolecular `I….O` interactions linking molecules together. The oxides `I_(2)O_(4)` and `I_(4)O_(9)` are moderately stable, though less stable than `I_(2)O_(5)`. `I_(4)O_(9)` is a yellow hygroscopic soild, which can be made as follows:
`2I_(2)+3O_(3)rarrI_(4)O_(9)`
`HIO_(3)overset(P_(2)O_(5) or H_(3)PO_(4))underset(-H_(2)O)rarrI_(4)O_(9)`
It decomposes to when heated above `75^(@)C` .
`4I_(4)O_(9)rarr6I_(2)O_(5)+2I_(2)+3O_(2)`.
On the hand, dehydrating `HIO_(3)` with concentrated `H_(2)SO_(4)` gives `I_(2)O_(4)`. This is a lemon yellow soild. It also decomposes to `I_(2)O_(5)` when heated above `135^(@)C`
`5I_(2)O_(4)rarr4I_(2)O_(5)+I_(2)` .
The structures of these oxides are not well known, but `I_(2)O_(4)` is probably `IO^(+)IO_(3)^(-)` and `I_(4)O_(9)` is probably `I^(3+)(IO_(3)^(-))_(3)`.