Since this reaction is ArNH2+NO2 −+2H+→ArN2 ++2H2O, it theoretically requires {HEAD ~ two equivalents} of {TAIL ~ an acid} 
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Since this reaction is ArNH2+NO2 −+2H+→ArN2 + +2H2O , it theoretically requires { HEAD ~ two equivalents } of { TAIL ~ an acid }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL