Question

Consider the reaction that occurs when copper is added to nitric acid. mc024-1.jpg What is the reducing agent in this reaction? Cu NO3– Cu(NO3)2 NO2

Answer 1

The reducing agent is copper

Answer 2

This question requires understanding of oxidation states and differentiating between a reducing agent and an oxidizing agent. An oxidizing agent gains electrons and is reduced, which means the oxidation number decreases. A reducing agent loses electrons and is oxidized, which means an increase in oxidation state.

In the equation,

$Cu_(_s_) + NO_3_(_a_q_) ==> Cu(NO_3)_2 + NO_2_(_g_)$

Cu in the solid state has 0 charge but in $Cu(NO_3)_2$ it loses 2 electrons to become $Cu^+^2$ ion with a +2 charge, while nitrate $NO_3^-$ gains electrons to become nitrite $NO_2^-2$,  -2 charge. Therefore we can conclude that Cu is the reducing agent.