A dilision of "VID\ --r.Ri'HI .{CADEMY PVT. LTD." JEE & NEET (b) Pressure correction or effect of molecular attrsction forces - A molecule in r: :::idle in of ;.:::;::* is atlracted unifomrly on a-r s-jes rniiile of cL::.a^t.Iter rnolecule collision b1 le:;:luring molecules. Therefore ll::e is no ris::::i1: ai:rracd\.e fOrCe On the molecu.e. Bu: ''..::,':: --::e :nolecuie approaches the u a.- of con:e-:::: i'.::ore collision,it lvould experienc.- atira;:ii: :-orce;rom the bulk ofthe molecules beiii:-. Due io:hl=se attractive forces speeri durilg col;isio:: ri:I bereducedas momentum rrill r; ie:<ser- i-rrc: epplied onthewall be will be Iess L)lpre-<s'Jre.;-i1l be lesser. .'. P,,j".r= P - lcorrection tenn,}' -+ correction term o no. of molecules attracting the curl.iiir:g molccule { l v r correction term cx densit-r' of molecules (n/v) -+ no. of collision a densitv ofmolecules (n/r,) net correction term u (n 1v)(n it'): an: / v 2 -a- is aconstant ofpropodionality * 'a' is dependent on forces of attraction. Stronger the tbrce of attraction gteater will be 'a' ,1tt' ... Vander waal's equation is (P = , + )(V-nb) : nRT. Verification of vander lvaal's equation I Vandu wall equation for I mole (r*-1.]," - b\= Rr [' - r't,Jt'-u) - r\1 z:l P _____+ Variation of ZwithP forvanderrvaal equation at any temperature At lorv pressure : At lo\ir pressure V will be high. Hence b can be neglected in comparison to v. But a/v2 can't be neglected as pressrire is also low. Thus equation rvould be ,/^\ lp"*l.r=nr +pL,+9=RT \ r-J t' I Forz<l : rl I Vreal<Videal' ' n*aT gas il eeiily compressible in comparison i.rr an icleai gas. At high pressure : V will be low so b can't be neglected in comparison to V. But a/V2 can be to a much higher value of P. Then vander q'aal Regd. Off.: 201, Znd Floor, Safal Pride Tower, Sion Trombay Road, Deonar, Chemhur, Ilumbai_4000gg. t. PL'uu RT I,'RT lR7' Anrlheri-fE\: ?.fiflii0?< fhpmhurrH n I. ,<<annl7/caq no.rn- /\.r! P:P+ j.- I f,'t f \ \
A dilision of "VID\ --r.Ri'HI .{CADEMY PVT. LTD." JEE &
NEET(b) Pressure correction or effect of molecular attrsction
forces - A molecule in r: :::idle
in of ;.:::;::* is atlracted unifomrly on a-r s-jesrniiile
ofcL::.a^t.Iter
rnoleculecollision
b1 le:;:luring molecules. Therefore ll::e isno ris::::i1:
ai:rracd\.e fOrCe On the molecu.e.Bu: ''..::,':: --::e :nolecuie
approaches the u a.- ofcon:e-:::: i'.::ore collision,it lvould
experienc.-atira;:ii: :-orce;rom the bulk ofthe moleculesbeiii:-.
Due io:hl=se attractive forces speeridurilg col;isio:: ri:I
bereducedas momentumrrill r; ie:
