Question

In the ionic equation for the reaction:
$I{O}_3^{-}+H^{+}+a{e}^{-}\to I^{-}+H_{2}O$
the value of 'a' is

• A. 2
• B. 4
• C. 6
• D. 10

Answer 1

The correct option is C 6

This is a reduction reaciton where the oxidation number of $I$ changes from +5 to -1.

Step -1 Balance atoms other than $H$ and $O$
$I{O}_3^{-}\to I^{-}$
Step -2 Balance $O$
$I{O}_3^{-}\to I^{-}+3H_{2}O$
Step -3 Balance $H$
$I{O}_3^{-}+6H^{+}\to I^{-}+3H_{2}O$
Step -4 Balance Charge
$I{O}_3^{-}+6H^{+}+6e^{-}\to I^{-}+3H_{2}O$​​​​​​