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CHBMISTRY 20
B-9
Lesson# 11
IntermolecularForces
1r,,.
'nc&r
o"ec jppSt in Fijrrc G9 whcn rrursinC
tI
l
o
I
i, 6 rod ? fono*ing
t\,
x-il-.
\
,'N#
""\
Doif4
Fid
.C
eEsri*
-tOO
\=
.{",".
Norc: The venical colunat of mmpunds (e-g-- H= Te.
SbHr, HI irnd SnH.) are boclcctronic.
Nrrnbtr
of EJ.di!.t
Frgurt G9: Boiling poins fcHydiqat
Compomds of
Grurp IVA Group VA, Grqrp VIA rnO Croup VUe5. Thc hydrogcn comPqrds of Groups v,\ vrA snd vIlA clcmcats bavc
incrcasing van dcr waals.forccs (crccpt for tbc lirs hy&ogen compounds) with incrcasiog numbcr of clcolms. Erplain why tbc boiling poim
of thc
firsr hydrogen cornpounds o{Group VA, ytA and \rtIA clgmcns bavc boiliry p"ios _*l
nighcr rhan cxpcctcd.
-/
hr-"f 4qtVt"nt&,,cF 4Lc tI qp-pt
tn1{,O\o
t vry
L-'-r"'*{
[.,'.ro-5i{.,gpi t{*t tt* r-,th'r do ,^.1-.
6- Explain why CIL thc first mcmbcr of Gmup IVA hydrogcn compourds, docs not havc rhe unslpecrcdly
point displaycd by thc hrst hydrogcn compowrd of thc othcr clcmcnts.
high boiling
Nn hlrUaie"-bctryls
e!
7- Thc boiling poins of thc hydrogen compoundsof the Group IVA clcmcns arc coruidcrably lowcr rhan rhc boiling poinrs
of thc c-bcr hy&ogcn compounds. Give a rcasonfor rhis cffcct.
T*ry'I
A e\?N*5
"4(-vlaurn-
L tl--r''Lo-^.
-t-,tp-,rt{*"J
Dsg-ir^ G.,.ns t-')tr! cYJ\ uvl- Q-D.).
.r2tppen,:,n-t-{i:
.-S
.
"--ff,
CHEMISTRY20
B-9
Lesson# ll
IntermolecularForces
'-)-ct'-':
explainwhy BrFand
1. In termsof bondingforcestrength,
CrHuhavedifferentboilingpoints.
-br('
45",-
V.-> <;Tva,r'<yrwUDF-I
DDF's
Vr..( t+vT1o"/
havedifferent
boiling
whyCH3OCH3
andCzHsOH
2. Explain
pointsyetthesame
numberof electrons.
'&+1,
lp
--J-J-.o+q
.T
I
.o- -,,
ctt's
DrJt=t':' cz l{s''::i] Pe5'dsj't€
s
hrv'e-'-0":t
A13A'.j r.:,:t1-.d a*1. fAnak-rc- h',fv t .Dif-^.i p"i^1.
explaih
f romCH+to CsH12
3. Forthe seriesof compounds
whythere'sa gradualincreasein boilingpoints.
fuc',nt Qor\o-.*1k-S
\{o.iTe^. LPF-s .
{Ve-a'u: hx>'-i -\o-'J',a'-o r?^o{ g--r
4. ExplainwhyCH3Fhasa slightlyhigherboilingpointthan
CrH;.
-*,Q.fr-r*s
DDF's
\cirLr,r-(.
s-) t-tf':
'l s-o
y-,QJ tr+-<
or?- 'nr^iV6
o\-\
brh
---)
i-L{ rtz;r+*- vlsn^-'hf e'F
'v-e*"i(C llaF
9<''S'#sl=5
in boilingpointsfor ClzandCoH,o.
S.Eipiainthe difference
YlO Dt)l:'t ho llSi-'s 5vl
1CW-- n,t^vy\-- nFric.-t+".S, i5oele,")W:d-tz,
cll-.,s.qv-"l.'r i'-.b'''|z:'zf''r e-')[-'1- '
C1l{,o is lct7er rt,l ;++ tt'-.
,
Ar andFzhavethesameboilingpointof
tb.Explain'why
-1 B6oC '
kn w,A €, 0/r' 13o.'\ttt*n'*
cna,*l,+, LDF's
?:
t-
rf '- r-"r Lr
\
havingthe samenumber
T.lf Kr andHBrareisoelectronic,
in their
thenwhatcausesthe largedifference
of electrons,
boilingPoints?
.^
Q"n'\--' hrS
b ty
l1{3r
'1
t-. D-t-.
y! ..1s-.
Tlor
\"t> t Fs h"''' b Di: i
t'ru, Pk
A/^A t\--veV'rc C t"1F" f''
j
P,"g
V
F
F
B[
1. Make a chart comparingthe following compoundsby identifying the intermolecularforces that exist
within eachcompound. Then rank them in order from lowest to highestboiling point.
# electrons
Compound
JzHe
ri ( 'b
l,'tO-'t
r8
cII3OIr
CsHrz
4'L/
CrHsF
4-1,
HBF
V
tz\ 51.\
i.ffJlotf
t
L/
L\
lrc^' JK
t .t
fhr
..,
/-
1
t-./
t/
I
2. Make a chartcomparingthe following compoundsby identifying the intermolecularforcesthat exist
within eachcompound.
CrHzF
CTHzOH
CcHro
rF
( Vr
Cj A-roil
t. r{, f-
-li*i
3.I
1o;i,'-
3r-(
i\n^li
v
.3r,1
tutt.
C,tt1.,
C1 Ll'to
\r-(
r
r
l
\c,i
ilan
-L--L ^r0-r-ltl
7r1.d1,1
V \
LDi:
CrHzNHz
r)[)tr
l?--.*tq
Z
l,4\)
V
l/
''
/
/
l,i o
t/'
C -
r--- (-'-
Nl
,io
, a n a .
\\.,a
l
t htttqt, h".A
FilF
j
l / '
?- hrd.,3a,
b.^lt
.J
t . ft-
t\J
/
V
I
V
;1 {)
Po\t^'r
Rank
'6C
h'?
po\r'r
9rt
CzHCI
DDF
LDF
Polarity
t
\
PRACTICEQId/.ZQUESTIONS
a
1 . Whichcompound
is mostlikelyto bea solidatroomtemperature?
FHr
AsH3
inx-hi/"; 'i.r^.
sbHs
it*^.- 1".',-d ail
2. Which substancehasdipole-dipoleforces?
Fz
CHa
'i/f't
I
ln*-,, pJ';f
po\cr
COz
E ^ r t ,
\__-./
i{ -- ur-
t''s\
p'-i.nz
Di, i o"-
\
J.
Which solid is held togethermainly by London DispersionForces?
IIF
NaCl
k%1..^i
faiiF t
i1,g(
fr,nn^a
/dHn
HzO
4. Which substanceexhibits hydrogenbonding?
Hz
CH:F
NOz
5. Which one of the following compoundswould have the highestboiling point?
CHTCHzCHT
t-pi:
cH3ocH3
TCHzOH
t-oF
l0F
cH3cH2F
t_ r)r:
Duf
Lotj
Doi-:
6. Rank the following substances
in orderfrom lowestboiling point to highest
boiling point.
CzFI.e
NaCl
CsHrz
CaHqF
W
innt'c
( bP
t-o1T)DF
b
i$r'
I
4Lo-
L
Lv{
DDT
eLe/
4
Mg
CzHCI
i
CH3OH
LoF
i;1-etrt,
b pr--'
f\13F:
1rr'.-
{
,
s
-
\