A student investigates the reaction between nitrate ions and iodide ions in an acidic…
CHEMISTRY · Multi-part · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions
Problem
A student investigates the reaction between nitrate ions and iodide ions in an acidic aqueous medium. The skeletal (unbalanced) equation is
NO3−+I−→I2+NO
The student is asked to analyze the redox characteristics of this process before attempting any numerical balancing.
(a) Assign the oxidation number of each element in every reactant and product species shown in the skeletal equation.
(b) Identify which species is oxidized and which is reduced. Justify your answer in terms of the oxidation-number changes you determined in part (a).
(c) When the overall equation is separated into two half-equations, extra electrons will be required on one side of each half-equation. Explain qualitatively (no calculations required) how the placement of these electrons guarantees conservation of charge.
(d) Describe two independent checks a chemist can perform to verify that a proposed final equation for this reaction is correctly balanced.