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Physical Chemistry

Blazing goIITian

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27 Jan 2008 18:29:57 IST

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642

DOUBT OF VP

None

LOWERING OF VAPOUR PRESSURE IS HIGHEST FOR

1) UREA

2) 0.1 M GLUCOSE

3) 0.1 M MgSO₄

4) 0.1 M BaCl₂

GIVE UR REASONS

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Comments (14)

Ananth Patri

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27 Jan 2008 18:32:09 IST

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colligative propertis deped on Mol wt....so which has more molwt will lower the vapour pressure to a greater extent....at same conc....thus u can cal.....

drishti sharma

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27 Jan 2008 22:13:00 IST

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urea (NH₂CONH₂₎in this i=1

0.1 M glucose: in this i=1 ;so as same as above. in MgSO_{4^{i=2 &in BaCl}2}i=3

So the vapour pressure will be more for BaCl_2^.

note - i is directly proportional to vapour pressure.

drishti sharma

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27 Jan 2008 22:14:35 IST

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hope satisfied from above explanation if not then ask again!!!!!!

drishti sharma

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27 Jan 2008 23:45:28 IST

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AND NOTE VAPOUR PRESSURE

BOILING POINT

Pankti Kansara

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28 Jan 2008 14:59:56 IST

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i think d ans is: 3)

V.P. is a colligative property n so it will change on association or dissociation

nw urea n glucose won't dissociate

MgSO4 will dissociate into Mg2+ n SO4 2-

since Mg n SO4 form an ionic bond its degree of dissociation can b considered to b 100%

BaCl2 will dissociate bt since it is a covalent compound its degree of dissociation is very low

so d ans is MgSO4

plz corr if der is some mistake............

srk

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28 Jan 2008 17:03:28 IST

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I THINK BOTH PANKS AND DRISH R CORRECT
BUT THEN WHAT'S THE ANSWER
WHEN I SEE D SOLN OF DRISH I THINK HE IS CORRECT
AND WHEN I SEE AT PANKS SOLN I THINK HE IS RIGHT
PLEASE GIVE A PERFECT SOLN

sowjanya gudipati

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28 Jan 2008 17:31:09 IST

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hey it is option 4.

coz in solution the no of ions will be more for this only

Himanshu

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28 Jan 2008 17:55:26 IST

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we knw

(delta) P / P^o = i . x_B

AS P^o n x_B are same for all solutions ,

delta P prop. to i

for MgSO₄ , i = 2 (approx)

urea , glucose its 1

BaCl₂ , i = 3

so its max for BaCl₂ , i think u can understand it

Ronde vous Silvouz plait

Blazing goIITian

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28 Jan 2008 18:16:45 IST

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hey chimanshu, can u solve my parabola doubt??

Pankti Kansara

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28 Jan 2008 20:04:12 IST

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sry himanshu bro........

bt i ws tld dt i fr BaCl2 is mch lessr than MgSO4 n its nt 3

plz clear my doubt yr......

srk

Blazing goIITian

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29 Jan 2008 00:17:24 IST

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SORRY GUYS IT IS LATE
BUT HOW D VALUE OF i CAME
IF U DONT MIND CAN U EXPLAIN PLEASE

Akhil

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29 Jan 2008 10:24:29 IST

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Sagar90, for ionic compound which dissociates into ions, u can just add total no. of ions...eg
NaCl will give Na+ and Cl- so 2
Na2SO4 will five 2 Na s and 1 SO4 so i=3
but note that it does'nt hold for covalent compounds!

Himanshu

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29 Jan 2008 21:09:03 IST

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BaCl₂ -----> Ba²⁺ + 2Cl^-

so V.H.F = 1 + 2 = 3

MgSO₄ -----> Mg²⁺ + SO₄^2-...

V.H.F = 1 + 1 = 2....

any doubts?

srk

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29 Jan 2008 21:36:13 IST

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ya i understood
thanks

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