1. The problem statement, all variables and given/known data Which substance is the oxidizing agent in this reaction? 2CuO + C = 2Cu + CO2 2. Relevant equations 2CuO + C = 2Cu + CO2 3. The attempt at a solution According to the online program I'm using for homework, CuO is the oxidizing agent, but I don't understand why. The oxidizing agent is the substance that gained electrons. Cu had an oxidation state of +2 prior to the reaction, and ends up gaining electrons to form neutral Cu. Each oxygen had an oxidation state of -2 prior to the reaction and ends up with -2 after the reaction. Carbon has an oxidation state of zero prior to the reaction and ends up with +4 after the reaction since it is reduced. So 4 electrons are taken from carbon and given to 2 copper atoms. Shouldn't Cu be the oxidizing agent here? CuO doesn't even exist after the reaction, so how can it have gained electrons?