AP Chemistryeasymcq1 pt
A solution is prepared by dissolving 2.00 mol of urea in 800. g of water. What is the molality of the solution?
A.2.50 m
B.2.00 m
C.1.60 m
D.0.400 m
Explanation
Core Concept
Molality divides moles of solute by kilograms of solvent, never by liters of solution. Converting the solvent mass, 800. g equals 0.800 kg, then 2.00 mol divided by 0.800 kg gives 2.50 m. Urea is a nonelectrolyte, so no dissociation factor multiplies the result. Watch the unit convention: dividing by grams instead of kilograms would report a number a thousandfold too small.
Correct Answer
A2.50 m
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