m(C2H5OH)=n*M=0,2*46=9,2г, m(р-ра)=m(H2O)+m(C2H5OH)=200+9,2=209,2г. w(C2H5OH)=m(C2H5OH)*100%/m(р-ра)=9,2*100/209,2=4,4%. ответ: w(C2H5OH)=4,4%.
m(C2H5OH)=n*M=0,2*46=9,2г, m(р-ра)=m(H2O)+m(C2H5OH)=200+9,2=209,2г. w(C2H5OH)=m(C2H5OH)*100%/m(р-ра)=9,2*100/209,2=4,4%. ответ: w(C2H5OH)=4,4%.