Posted by a on .
assuming complete dissociation of the solute, how many grams of \rm KNO_3 must be added to 275 \rm mL of water to produce a solution that freezes at 14.5 ^\circ {\rm C}? The freezing point for pure water is 0.0 ^\circ {\rm C} and K_f is equal to 1.86 ^\circ {\rm C}/m.

chemistry 
DrBob222,
delta T = i*Kf*m
Solve for m.
m = moles KNO3/kg solvent
Solve for moles KNO3.
moles KNO3 = grams KNO3/molar mass KNO3
Solve for grams.
i = 2