Question

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

Answer 1

solution : - Molarity = 3 mol L

Mass of 1 L solution = 3 × 58.5 = 175.5 g

Mass of 1 L solution = 1000 × density
= 1000 × 1.25
= 1250g

Mass of water in solution = 1250 - 175.5
= 1074.5 g


Hence ,

molality ( m ) = Moles of solute
-------------------------
Mass of solvent in kg

3
= -----------
1.0745


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