The density of 3 M solution of Nacl is 1.25g / L calculate the molality of the solution?

Question

ujjwal · Answer

gm/liter=molarity * molecular weight

anonymous · Answer

We r given all the three

anonymous · Answer

@Vincent-Lyon.Fr Plz help me!

ujjwal · Answer

oh, it is asking for molality.

mathslover · Answer

Hmn .. Class XI some basic concepts of chemistry

mathslover · Answer

3M soln=175.5g in 1000ml of soln right ?

anonymous · Answer

yup

mathslover · Answer

i.e 175.5 g in 1250 g of soln or 3 moles in1074.5 of solvent or 2.79 no of moles in 1000g of solvent. right ?

anonymous · Answer

ok......... if the density is 1.25 g /ml then

anonymous · Answer

also the answer is same!!

mathslover · Answer

attachment

mathslover · Answer

Sorry i am having exams cant help u now BUT i am sure that that will help u

anonymous · Answer

@mathslover  u see my question is density is 1.25 g /L

anonymous · Answer

not ml....

mathslover · Answer

Why not to just put 1.75 instead of 1.25 ?

anonymous · Answer

hey i am serious!

anonymous · Answer

PLzz

anonymous · Answer

The density of 3 M solution of Nacl is 1.25g / L calculate the molality of the solution?

ujjwal · Answer

Do you have the answer?

anonymous · Answer

nop!

mathslover · Answer

@ujjwal can u help him further with the basis of the image ( soln ) of the simiar question given by me ?

anonymous · Answer

if the density is 1.25g/ ml then the answer is 2.79

anonymous · Answer

but my ? asks for 1.25 g /l

ujjwal · Answer

How do you do it when the density is 1.25g/ml?

ajprincess · Answer

convert l into ml

anonymous · Answer

by using maths lover attached a photo

anonymous · Answer

http://assets.openstudy.com/updates/attachments/500e870be4b0ed432e10c888-mathslover-1343130148132-yahoo.jpg

ujjwal · Answer

So, put the density 1.25 $\times10^{-3}$g/ml and then solve it!

anonymous · Answer

thxxx

ujjwal · Answer

Well, I have this formula too. May be it will help you too..
$$\textrm{molality}=\frac{\textrm{wt. of solute}\times 1000}{\textrm{mol. wt.}\times\textrm{wt. of solvent (gm)}}$$

vincent-lyon.fr · Answer

@mathslover gave the right answer, considering the typo in the question.

The density of an aqueous solution must be around 1 (non dimensional)
That means the volumetric mass is around 1000 kg/m³ = 1000 g/L = 1000 mg/mL, whichever you prefer.

1.25 g/L roughly corresponds to air in standard conditions !!