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## Lena772 one year ago Determine the osmotic pressure (in atm) , at 80.2 o F, of an aqueous Iron (II) nitrate solution whose mole fraction of solute is 0.002696. Density solution = 1.11 g/mL

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1. Lena772

PV= nRT So Posm = nRT/V R= 0.08206 L*atm/mol*k T= 80.2F = 299.928 K V = calculate somehow using density n = reverse mole fraction calculation to find total moles of solution

2. Lena772

@taramgrant0543664 @photon336 Can you guys assist me in reversing the mole fraction equation to find total moles of solution and then using that calculation with the density to find volume?

3. taramgrant0543664

V=m/d where v is volume, m is mass and d is density

4. Lena772

right, but i can't find the mass of the solution until i reverse the mole fraction and find moles of total solution

5. Lena772

I think? Mole fraction = (moles solute) / (moles solute + moles solv ). We are given moles of solute, but I don't know where to go from here. :(

6. taramgrant0543664

Yes that is the formula

7. taramgrant0543664

You're not given moles of solvent?

8. Lena772

@Abhisar @pooja195 @zepdrix @abb0t

9. Lena772

Nope. :/

10. taramgrant0543664

Hmmm... I don't know to tell you sorry I've only touched on osmotic pressure stuff none of my profs or teachers really talked much about it so I don't want to lead you on the wrong direction

11. Lena772

Do you know anyone online that can help me? @taramgrant0543664

12. taramgrant0543664

I think you got a majority of the ones that could hopefully help

13. Lena772

@abb0t Do you think you can help me?

14. Lena772

@NoelGreco Hi! Can you please help me?

15. mayankdevnani

@Lena772 can you find out molality ?

16. Lena772

yes moles solute/kg solvent. But I don't know the moles of solute.

17. mayankdevnani

Here is a formula :- $\large \bf Molality=\frac{X_{solute}\times 1000 }{(1-X_{solute}) \times M_{solvent}}$

18. mayankdevnani

and then use this :- $\large \bf Molarity=\frac{molality \times density \times 1000}{molality \times Molar~ mass~ of~ solute+1000}$

19. mayankdevnani

hope you can find molarity

20. Lena772

Molal = (0.002696 mol Solute * 1000) / ( 0.997304 * molality of solvent) , BUT idk the molality of the solvent

21. mayankdevnani

its molar mass of solvent

22. mayankdevnani

not molality of the solvent Remember molality is denoted by small m i.e m

23. Lena772

Molal = (0.002696 mol Solute * 1000) / ( 0.997304 * 175.8948)

24. mayankdevnani

after you find out molarity ! Use this :- $\large \bf Osmotic~Pressure(\pi)=Molarity \times RT \times vant~hoff~factor$

25. Lena772

0.015368778 molal ?

26. mayankdevnani

i don't know. Use calculator

27. mayankdevnani

i am here to give you HINTS as possible

28. Lena772

molality = 0.94396197 0.94396197 * 0.08206 * 299.928 K * van hoult?

29. mayankdevnani

you don't know vant hoff factor ?

30. mayankdevnani

denoted by i

31. mayankdevnani

@Lena772 then first learn this term and then solve the rest of question

32. mayankdevnani

any problem ???

33. Lena772

Would the factor be 4 because there is 3 pieces of iron nitrate and 1 piece of water molecule?

34. Lena772

@mayankdevnani

35. mayankdevnani

nope ! try again

36. Lena772

What's wrong about it?

37. mayankdevnani

see the oxidation state of iron in question. You took the oxidation state as +3

38. Lena772

So van hoff is 3 ?

39. mayankdevnani

yup

40. Lena772

I get 69.7 atm. That's sounds extreme. Can you just plug those in and see if you get the same value?

41. mayankdevnani

lol but i don't have much time to solve ! Sorry ! Better luck ,Next time

42. mayankdevnani

i have to go now ! Bye ! @Lena772 Its been a nice time with you ! :)

43. mayankdevnani

MEDAL for your HARDWORK and keen interest on solving this question !

44. mayankdevnani

REMEMBER :- Don't suppose that i am a professor, i am (18)-

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