The Equation goes as follows:
C2H5OH + NAD+ ----> C2H4O + NADH + H+
Its an enzymatic reaction. The Enzym oxidizes the Ethanol into Acetaldehyde and reduces the NAD+ into NADH and into a free Proton.
My question was where the free Hydrogen comes from. Im somewhat of a chemistry beginner so bear with me but I'm not quite understanding what is exactly going on