Consider the oxidation of ethanol CH3CH2OH to acetaldehyde CH3CHO by NAD+. a) State half reactions for the process. b) NADH is biochemical reducing agent, in the reverse of the oxidation reaction. State half-reactions for the reduction of pyruvic acid (CH3COCOOH) to lactic acid (CH3CHOHCOOH) by NADH, as well as then combine these two to get the equation for overall reaction.