How much ethyl alcohol (C2H5OH) must be added to 1 L of water so that solution will not freeze at -6oF?(Kf of H2O=1.86omol−1kg)

−6oF is to be converted into  oCF−32180= C100−4−32180=C100∴ C=−20oC∴ ΔTf=20oC1 L H2O=1000 g waterΔTf=1000 Kfw1m1w2w1 (ethyl alcohol)=ΔTfm1w21000 Kf=20×46×10001000×1.86=9200001860=494.6 g