C2H4O+Ag2O=C2H4O2+2Ag

1                                     2

n(C2H4O)=0,5:44=0,0114моль;n(Ag)=2*0,0114=0,0228моль;m(Ag)теор.=0,0228Х108=2,455гр.

                                   2,455гр.   -         100%

                                   2,16(практ.)           Х%

                                                             Х=    87,98%             

       Ответ:массовая доля выхода=87,98%