basic molality doubt
Online solutions multiply molality with amount of solution to get moles, shouldn't it be amount of solvent? Thanks
21 Replies
@Dexter
Note for OP
+solved @user to close the thread when your doubt is solved. Mention the user who helped you solve the doubt. This will be added to their stats.*weight, not amount
Answer is a?
Correct
Ignore that physics
But aren't they saying 1 Kg solution
As molality is in terms of solvent not solution
Lemme check
Bro I think I too need answer from seniors 💀
Btw which book is this?
I thought it's a question that checks if we remember the definition of molality but online solutions show otherwise
Coaching module
Bro I think then question is wrong along with me and you seem correct 💯😭
https://m.youtube.com/watch?v=EWVzNVKofmE
Here they multiply weight of solution with molality to get number of moles, same as the solution you sent
@iTeachChem gurudev Apka intzaar ho rha Hai🙏
you gusy fdigured this out no?
and yea not amount, mass. when the multiply with mass of solution, it may be cos it is really dilute so mass of solute doesnt matter much, perhaps
Bro what are you typing from the past hour?
Was typing out the solution
I made some mistakes in my previous calculations, sorry about that
It's given that we have 2m and 4m solutions of urea
ie 2 mol urea per kg water
And 4 mol urea per kg water
Since urea is 60g/mol
In the first solution,
120 g urea per kg water
120 g urea per 1.12kg solution
Similarly for second solution
240g urea per kg water
240 g urea per 1.24kg solution
They take 1 kg first soln and 2kg 2nd soln
So total mass of urea taken is (120/1.12)+(2)(240/1.24)g
=107g+387g = 494 g
i.e. approx 8.2 mol
Total mass of water taken would be 3Kg - mass of urea
= 2.5 Kg
m = 8.2/2.5 = 3.28m
Approx 3.33
Yes, I think we can take solution and solvent weight to be the same if molality is very small
But this is very risky💀
Ok sir understood 🫡
+solved @iTeachChem
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