Assuming complete dissociation of the solute, how many grams of kno3 must be added to 275 ml of water to produce a solution that freezes at −14.5 ∘c? the freezing point for pure water is 0.0 ∘c and kf is equal to 1.86 ∘c/m. express your answer to three significant figures and include the appropriate units.

108 g of must be added

Explanation:

is a strong electrolyteFor an electrolyte dissolved in a solution- is depression in freezing point of solution, i is van't hoff factor (equal to number of ions produce from dissociation of 1 molecule of electrolyte) and C is molality of solutionMolar mass of is 101.1 g/mol and density of water is 1 g/mLSo, mass of 275 mL of water is 275 gWe know, molality = (number of moles of solute)/(mass of solvent in kg)If W g of must be added then For , i = 2 ()Here

So,

or, W = 108

So, 108 g of must be added