J.R. S. answered 05/18/22
Ph.D. University Professor with 10+ years Tutoring Experience
The equation to be used for the freezing point depression and boiling point elevation is
∆T = imK
∆T = change in freezing or boilling point = ?
i = van't Hoff factor = 2 for AgNO3 since it dissociates into 2 particle (Ag+ and NO3-)
m = molality = 1.75 m
K = freezing or boiling constant for water (assuming the solution is aqueous)
Kfreezing = 1.86º/m
Kboiling = 0.512º/m
Freezing point calculation
∆T = (2)(1.75)(1.86) = 6.5º
New freezing point = -6.5ºC since water normally freezes at 0º
Boiling point calculation
∆T = (2)(1.75)(0.512) = 1.8º
New boiling point = 101.8º since water normally boils at 100ºC