New Worksheet - Chemistry - Molality

Directions: Using these formulas, solve the following problems.

molality = mol solute / kg solvent
1 amu = 1 gram / mol
ΔTfreezing = (- number of ions) (molality) (kf)
ΔTboiling = (number of ions) (molality) (kb)
kf and kb are constants for each individual solvent

Problem 1: What is the molality of a solution containing 611 g of Hg(CN)2 dissolved in 6870 g of methanol?
Answer: _______________________

Problem 2: What is the molality of a solution containing 19.3 g of NaCl dissolved in 396 g of water?
Answer: _______________________

Problem 3: How many grams of NaOH would be required to produce a 5.72 m solution with 942 g of water?
Answer: _______________________

Problem 4: How many grams of KCl would you need to dissolve in 191 g of vinegar in order to prepare a 1.21 m solution?
Answer: _______________________

Problem 5: Calculate the molality of 5.89 g NaCl dissolved in 416 g of water.
Answer: _______________________

Problem 6: Calculate the molality of 1.43 g Na2CO3 dissolved in 315 g of water.
Answer: _______________________

Problem 7: Calculate the molality of 5.18 g KBr dissolved in 124 g of water.
Answer: _______________________

Problem 8: What are the new boiling and freezing points for a solution with 591 g KBr dissolved in 7960 grams of water? (kb water = 0.512˚ C/m and kf water = 1.86˚ C/m)
Answer: _______________________

Problem 9: What are the new boiling and freezing points for a solution with 637 g NaOH dissolved in 1596 grams of water? (kb water = 0.512˚ C/m and kf water = 1.86˚ C/m)
Answer: _______________________


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