Question

The density of 3M solution of Nacl is 1.25 g/ml . Calculate molality of the solution .

Answer 1

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Answer 2

molarity 3M means 3 moles of NaCl are in 1000ml or 1 L water
molality means no. of moles of solute present per kg of solvent
density of solution is 1.25 g/ml
=>wt of solution is 1.25 ×1000 = 1250 gm
wt of NaCl is 3×58.5 = 175.5
wt of solvent = 1250-205.5= 1074.5gm= 1.0445kg
molality = 3/1.0745 = 2.791m