24,2004
November
CHM l3ll: Exam#4
Page2 of l0
SSN (last 4 digits)
CHM 1311: GeneralChemistry1, Fall 2004
Exam #4, November24r2004
SSN(last4 digits)
KEV
NamefprinO
Pledge:I haveneithergiven nor receivedaid on this exam:
Signature
For ALL problems: SHOW ALL WORK TO GET FULL CREDIT
Usefulequationsand constants
1
,
KE = :mv'
2
T*",r,n: Trr,r,u,* 27 3' | 5
Xe =
- P o
n A + n B + n c + . . . Pro,ut
density = mass/ volume
pressure= force / area
AE-q+w
AH=AE+PAV
w=-PAV
"C-l]
heatcapacity- (specificheat)*(mass), [units = J
heatexchanged= (heatcapacity)*(Atemp)
For a manometer:(hu) * (dr) = (ho) * (do)
PV = nRT
[R = universalgasconstant= 0.0821L atm mol-l K-11
= Pa + P" + ......
Ptotul
1 amu= 1.66054*10-24g
1 mole = 6.022 x 10-" = Avogadro'snumber
,> -)
ljoule=1kgm s
1 cal = 4.184J
= Atmospheric pressureat sealevel = 14.7lbI in2
= 1 atm = 101,325pascals(exactly)
= 760.Otorr = 760.0 mm Hg
densityof Hg = 13.6grams/ mL
standardmolar volume of ideal sas= 22.41 L
I atm
1 . (3)
2. (4)
3 . (8)
4. (4)
5 . (6)
6. (4)
7 . (3)
DO NOT WRITEIN THESEBLANKS
ls. (3)
8. (8)
16. ( 3)
e. @)
r0. (3)
17.(s)
l 1. ( 3)
t2. (3)
18. (6)
r3. (3)
14. (8)
nA
te. (4)
20. (8)
2r. (4)
22. (3)
TOTAL (100)
November24,2004
CHM l3l1: Exam#4
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Name
SSN (last 4 digits)
1. (3 pts) Which one of the following is a unit of energy,but not an S[ unit of energy?
a. joule
b. newton
c. pascal
d. watt
r)*\
\!'Tcatorte
2. (4 pts) Which one of the following statementsis true?
kineticenergysincethey are in constantmotion,while molecules
a. Moleculesin gasespossess
no kineticenergy.
not
in constantmotion and hencepossess
in liquidsand solidsare
b. Moleculesin gasesand liquids possesskinetic energysincethey are in constantmotion,
while moleculesin solids are not in constantmotion and hencepossessno kinetic energy.
kineticenergysincethey are in constant
(i;Molecules in gases,liquidsand solidspossess
motion.
d. Polyatomicmoleculespossesskinetic energyin the liquid and gaseousstatessincethe atoms
can move aboutin the moleculeeven if the moleculecannotmove.
kineticenergyunlessthe solid is
e. Sincesolidsarerigid, their moleculesdo not possess
melted.
3. (8 pts)Whatvolumeof carbondioxidegasat 477. "C and750.torr canbe producedby the
combustion
of 32.5gof C2H2(MW=26.04g mol-')?
complete
CzHz+ 5l2oz (g) > 2 CO2(g) + H2O(l)
jZ;3
t.z:
C z t ' { r:
t . 2 i * , > t cl o. C z l l
ry"t< C2ll7 _
.l ;c
L-
r>u;/a C.c,
f V = m[ry
E * \K
. /V*: ' 7
Z-";t y,o\Z{ i
T(,r,
Q"l-Y., L
\ J
V
r^\;1(
}rO
tK
24,2044
November
CHM 13ll: Exam#4
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SSN(last4 digits)
chemicalreactionhasjust occurredin an insulatedisolatedsystem.
4. (4 pts)An exothermic
true?
belowis necessarily
Whichonestatement
by the system.
a. Heatwastakenin from thesurroundings
/-?\
( UJHeatwasgivenoff to thesurroundings
by the system.
\-/
c. The potentialenergyof the systemincreased.
(A Ttt. potentialenergyof the systemdecreased.
)s-\./
( e.lfhe totalenergyof the systemincreased.
5. (6 pts)A sampleof gasin a cylindricalchamberwith a movablepistonoccupieda volumeof
is
was27.2 "C. The pressure
was l.I2 atmandthetemperature
6.414L whenthepressure
by
the
sample
piston.
is
volume
What
the
occupied
readjusted
to 5.82atmby movingthe
remainsconstantthroughout?
underthelaterconditionsif thetemperature
a. 0.837L
b. 0.937L
or.23L
d . 1 . 5 3L
e. 3.34L
P,!', ":P'z"'-r[ , , L X L Ll lt l = a : ! ' L X v / ,
i' {L:
l,L3L
6. (4 pts)Whenaluminummetalreactswith iron(III) oxideto form aluminumoxideandiron
under
metal,429.6kJ of heataregivenoff for eachmoleof aluminummetalconsumed,
enthalpy
value
for
the
standard
correct
What
is
the
conditions.
andstandard
constantpressure
equationbelow?
of reactionin thethermochemical
2 Al (s) + Fe2O3(s) t
2 Fe (s) + Al2O3(s)
I
a. +429.6kJ
b. 429.6kJ
c" +859.2kJ
*859.2kJ
Ge. -1289
kJ
tt,
Lt", ft-y
n u) Lr Ls,,
7 LL7t- {16 ,"'} ,/t i:
Z t ( - 4 2 , 1, L i . l j = - , I \ . 1 L l , T
November24,2004
CHM 13ll: Exam#4
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SSN (last4 digits)
7. (3 pts) The boiling points of the halogensincreasegoing from F2 to 12. What type of
intermolecularforcesare responsiblefor this trend?
forces
London/dispersion
Fl I
b. hydrogenbonding
c. ion-ion attraction
d. dipole-dipole
e. ion-dipoleattraction
8. (8 pts) Given the following standardenthalpiesof formation:
A: +15.7kJ mol-l
D: --71.6kJ mol-l
C: -52.7 kJ mol-l
B: -86.4 kJ mol-l
What is the standardenthalpyof reaction,in kJ for the following reaction?
B + 2 A ) C + D
af l{" ',, C ,li (r ) | d t/r*c(,J) -
a. -195.0kJ
,/,; -,
w 4e.3kl
--*
c. -53.6 kJ
**f=< I
:-
d. +69.3 kJ
n
t
-
(.-\ c.q)\
f(-lt,t)
-Lci I
,
d/{.
ttT
e. +53.6kJ
9. (4 pts) As liquid nitrogen(-196'C) is pouredover a balloonfilled with air, the gasin the
balloonis cooledand its volume decreases.Use kinetic moleculartheory to briefly explain
in volumeoccurs(assumeno gasleavesthe balloon):
why this decrease
,-os( i'r
i1r-
?
)
-/-\
)
c--
t'Stt5
,u t- L-cc--(t,
f*u ,,*
l rl^,o-
)rln"ha
l
1i."4tL.) fu-l q tl..iQ ,o*t i,r'{-(.
I
i - r L t < - , 1 / . ) L )L 4 r ' r V . r . , \ ,
t
:"
!-i
ir.r, I I u-nn
e4
'
+i
Wi/LL\
,f* l.- tt\-"r f1"^
J
l g r s . ) tv
i
r) I u'lt1cv
b>./ /dJ)r- 1
C-y'<.
-
Vr -
4 5
+,-yt*,lat
,r^,,
(,
t
) L)
CHM l3l1: Exam#4
Pase6 of l0
November24,2004
Name
SSN(last4 digits)
10. (3 pts) Which statementbelow is true?
a. A statefunction is one whosevalue in a systemdependson the methodof preparationof the
reactantsand products.
b. A statefunction is one whosevalue in a systemis determinedby the temperatureof the
system,and not by the compositionof the system.
L./
statefunction is one whosevalue in a systemis determinedby the compositionof the
system,the volume, the temperature,and the pressure.
11. (3 pts) On a relativebasis,the weakerthe intermolecularforcesin a substance:
lower is its surfacetension.
f)ttre
b. the largerare the moleculesthat make up the substance.
c. the higheris its meltingpoint.
d. the more likely the substancewill be a liquid or a solid.
e. noneofthe above.
12.(3 pts) Considerthreeone-literflaskslabeledA, B and C filled with the gasesnitrogenoxide,
nitrogendioxide and dinitrogenoxide, respectively.Eachflask is at STP. In which flask do
the moleculeshave the highest averagekinetic energy?
a. flask A
b. flask B
c. flask C
( d.) all arethe same
13. (3 pts) The moleculesin a sampleof solid CO are attractedto eachother by a combination
of:
a. London forces and H-bonding.
b. H-bonding and ionic bonding.
c. covalentbonding and dipole-dipoleinteractions.
( dJ London forcesand dipole-dipoleinteractions.
Y non.ofthese.
November24,2004
CHM l3ll: Exam#4
Page7 of10
Name
SSN (last 4 digits)
equations:
14.(8 pts) Given the following thermochemical
t/,
€'
'rr.Hr(g)
t
N, (g) +
NH: (g)
AHo= -'kJ
calculateAH" (kJ) for the following reaction:
3 Mg (s) + Nz (g) )
a. 417 kJ
G.-',-lSl Ul
Mg3N2(s)
*'Lr r: ,"o,.Frrr"
, 1 fL- Sr-!., u 6
i'',".( i:..r.c-.r ,u,cz.,1.i--7^
G
y'{.,.1-FU,..,
c. +325k1
d. -325zu
e. -279 KI
15.(3 pts)An endothermicreactionis one in which thereis
a. a positivevaluefor the work (w > 0 joules)
b. a negativevaluefor the work (w < 0 joules)
c. a negativevalue for AH (AH < 0 joules)
(;l)
a positivevalue for AH (AH > 0 joules)
e. a negativevaluefor AE (AE > 0 joules)
16. (3 pts) Which of the following is the correctorder of boiling points for CaCl2,NH3, CH4,
He?
a. He < NH: < CH+ <CaCl2
b. CaCl2< NH: < CHa < He
c. He < CH+ <CaCl2< NHr
@m.
< CH4< NH: <CaCl2
e. CHa < He < NHr < CaCl2
November
24,2004
CHM l3l1: Exam#4
Page8 ofl0
SSN (last 4 digits)
17. (5 pts) You havea sampleof gasin a cylinder with a moveablepiston, as shown on the left:
In a specificprocess,the temperatureis increasedfrom 300 K to 600 K at constantpressure
(no changein numberof gasparticles). On the right above,redrawthe positionof the piston
in the apparatusto show what the samplevolume will be after the processoccurs(be as
accurateas possiblewith your drawing--i.e.if the volumedoubles,makesureyour drawing
reflectsa doubling):
18.An open-endedmanometercontainingmercury is connectedto a containerof gas. Consider
the situationwherethe mercury in the arm attachedto the gasis 57 mm higher than in the one
The atmosphericpressurein this experimentis 1.05atm.
opento the atmosphere.
(a) (2 pts) sketchon the diagramwhat the mercury levels look like:
ll
\ t' - 7
f\
TI
'+1 a
ll
|
100mm
(b) (4 pts) what is the pressureof the enclosedgasin torr?
i,Df
,,'tTn -= lr.
J'.S
t
!f
, - "1. , - ,
i
| 'r\ \-,i4r
{tr).r5
n *:,'"t..1w
=
}q
i),j.., t- i f ,n 0,.
(
,"rr.L. ,
November
24.2004
CHM l3ll: Exam#4
P a s e9 o f 1 0
Name
SSN (last 4 digits)
19 (4 pts) On the graphbelow, show how the temperatureof an ideal gas relatesto its volume at
constantpressure(be sureto label the axes):
t
T oK
/
I
ouL.V I
,..,,
l
L
-'* s
/ / \
20. (8 pts)When puresodiumhydroxideis dissolvedin water,heatis evolved. In a laboratory
experimentto measurethe molar heatof solutionof sodiumhydroxide(molar mass= 40.00
g/mole),the following procedurewas followed. To a calorimetercontaining300.0 g of water
at 20.00 oC, 10.65g of NaOH, also at 20.00 oC was added. The temperaturechange,which
was monitoredby a digital probe with negligible heatcapacity,stoppedwhen it reacheda
temperatureof 28.50 'C. If the specificheatof the NaOH solutionis 4. 184J g-' oc-t, and the
small heatcapacityof the calorimeteris ignored,what is the heatevolved,per mole of sodium
hydroxide?
a\- ;2, - Zr a,1,
- t_ \ :c, ,i
Ar :
a. -37.4kJ
G -41.5 kJ
l c't" i
c. -45.5 kJ
d. -90.5 kJ
9 [,''iLV =
9 t t . / r ,) :
e. -153 kJ
:
,r
t lu.- f,.nt>.rr.* t- i f
lu"-t
t i ne ' I t t " r i
\^4,v-:
1 : u L ) t , . J( r . . o ) /
J * _ 3 l c Or-,
I,U> LJ
,
-.-
tt.Af lt)
t
1 o . r -' ,
-- ( 2(.6 ,1,"k/-+,cl/
+
,
__ 4' rt,,
\ LT /t,,;(
') +
"
;\
LL"Grot-
pry
${.l'.."/'
tr l L +.\
i,fd H:'.
,, Jn
1 [a-,r*1t[q
I
{* + i
CHM l3ll: Exam#4
P a g e1 0 o f 1 0
November24,2A04
Name
SSN (last 4 digits)
2I. (4 pts) Considerthe GroupVIA hydrides(H2O,H2S,H2Se,H2Te).
a) Which hasthe lowestboiling point?
U' L 'J i
b) Which hasthe highestboiling point?
iJ.c
22. (3 pts) The viscosityof a liquid dependson
a) the ability of moleculesto tangle
b) temperature
c) intermolecularforces
(tllpll of the above
Vnone of the above