Question

In the balanced chemical reaction
$IO^{-}_{3}+aI^{-}+bH^{+}\to cH_{2}O+ dI_{2}$
$a, b, c$ and $d$ respectively corresponds to

• A. 5, 6, 3, 3
• B. 5, 3, 6, 3
• C. 3, 5, 3, 6
• D. 5, 6, 5, 5

Answer 1

Answer: (A)

$\overset{+5}{I}O_3^- + I^- +H^+ \longrightarrow H_2O + \overset{0}{I}_2$
(i) Oxidation half cell
(a) Balancing the numbers of atoms
$2 I ^{-} \longrightarrow I _{2}$
(b) Balancing charge
$2 I ^{-} \longrightarrow I _{2}+2 e^{-}$ ...(1)
(ii) (a) Reduction half reaction
$IO _{3}^{-}+ H ^{+} \longrightarrow H _{2} O + I _{2}$
(1) Balancing number of atoms
$2 IO _{3}^{-}+12 H ^{+} \longrightarrow 6 H _{2} O + I _{2}$
(2) Balancing the charge
$2 IO _{3}^{-}+12 H ^{+}+10 e^{-} \longrightarrow 6 H _{2} O + I _{2}$
Multiplying Eq. (1) by 5 and adding it to Eq.
(2)

Hence, $a=5, b=6, c=3, d=3$