試題詳解

9. Calculate the molality of C₂H₅OH in a water solution that is prepared by mixing 50.0 mL of C₂H₅OH with 100.0 mL of H2O at 20℃. The density of the C₂H₅OH is 0.789 g/mL at 20℃. (C₂H₅OH: 46.07 g/mol. Density of H₂O is 1 g/cm³).
(A) 0.086 m
(B) 0.094 m
(C) 1.24 m
(D) 8.56 m
(E) none of these