Asked Dec 10, 2019

If 500. g of water is added to a 75 g of a 2.5 molality NaCl solution, what is the mass percent of NaCl in the diluted solution?


Expert Answer

Step 1


Mass of water is 500 g.

Mass of NaCl is 75 g.

Molality of NaCl is 2.5

Step 2

It is known, 1 g = 0.001 kg

Therefore, mass of NaCl in kg is 0.075 kg.


The mathematical expression of molality is,


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Number of moles of solute Molality = Weight of solvent in kg

Step 3

Substitute the given value of molality and weight...


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Number of moles of solute Molality = Weight of solvent in kg Number of moles of NaCl 2.5 0.075 kg Number of moles of NaCl = 0.1875


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