Question

the density of 3 M solution of nacl is 1.25mL-1 . calculate molality of the solution​

Answer 1

ANSWER :-

☆ Given :-

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.

☆ Formula :-

• Density ➙ mass/volume

☆ Solution :-

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

➦ 3/1.07468 kg

➦ 2.7915 Molal ✧

∴ The Molality Of The Solution Is 2.7915 Molal