Answer to Question #184030 in General Chemistry for Aich80

Question

"Standard Redox Reactions"

1. Given the standard reduction potential for the half-reactions (V⁺³/V⁺², -0.26 V) and (Zn/ Zn⁺², -0.76V)? Will Zn reduce Vanadium (III) ions to vanadium (II) ions? Show your solution.

Answer 1

The usual source of vanadium in the +5 oxidation state is ammonium metavanadate, NH4VO3. This isn't very soluble in water and is usually first dissolved in sodium hydroxide solution. The solution can be reduced using zinc and an acid - either hydrochloric acid or sulfuric acid, usually using moderately concentrated acid. The exact vanadium ion present in the solution is very complicated, and varies with the pH of the solution. The reaction is done under acidic conditions when the main ion present is VO2+ - called the dioxovanadium(V) ion.