Question

density of 3 moles solution of nacl is 1.25 per ml .calculate the molarity of that solutions
find them molarity​

Answer 1

Answer:

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Question



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

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Solution



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3 Molar solution means  there are 3 moles of  NaCl salt in 1 Liter.  Molecular weight of NaCl = 58.44.    

Hence, there are 3×58.44 gms in 1 Litre of water.

Density =volumemass

Mass of 1 litre of solution = 1.25 gms/ml * 1000 ml = 1, 250 gms

V = volume of water added to make the solution

  175.32 gms + 1 gm /ml * V = 1, 250 gm

       ⟹V=1,074.68ml

So 1,074.68 ml or 1, 074.68 gms of water is mixed with 3 moles of Na Cl to make the 3 M solution.  

       

   Molality = mass of solute in number of moles / mass of solvent in kg

               =1.074683kg

               =2.7915 Molal 

Answer 2

Answer:

NaCl salt in 1 Liter. Molecular weight of NaCl = 58.44.

Hence, there are 3×58.44 gms in 1 Litre of water.

Density =

volume

mass

Mass of 1 litre of solution = 1.25 gms/ml * 1000 ml = 1, 250 gms

V = volume of water added to make the solution

175.32 gms + 1 gm /ml * V = 1, 250 gm

⟹V=1,074.68ml

So 1,074.68 ml or 1, 074.68 gms of water is mixed with 3 moles of Na Cl to make the 3 M solution.

Molality = mass of solute in number of moles / mass of solvent in kg

=

1.07468

3

kg

=2.7915 Molal

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