Question

Question 1.

A 2.700×10−2M solution of NaCl in water is at 20.0∘C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.3 mL . The density of water at 20.0∘C is 0.9982 g/mL.

a.)Calculate the molality of the salt solution.

B.) Calculate the mole fraction of salt in this solution.

C.) Calculate the concentration of the salt solution in percent by mass.

D.) Calculate the concentration of the salt solution in parts per million.

Question 2.

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.

Molarity = mole of solute/mass of solvent

mole of solute= molarity of solution/volume of solution

. = 0.0205M × 1.000L

= 0.02050

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