> ^]`!H<7DSiHx~>h
8>dxcdd``fed``baV d,FYzP1n:&n! KA?H1Z0@0&dT20L/ @201d++&1{~-`,@RF\7sd*a,&߰j$?a`R^
B=I9J=p{:Y@**Y.]`p\021)Wx ],`YF('f8ZNT\`!H}Pc_.(`m`
@ pdxcdd``fed``baV d,FYzP1n:&n! KA?H1Zq30afQ`5<%!vfjv,L!
~
Ay_g1Xr8 J? 7f>#I3p{TWwCdOpenR~C(tpb#ܞi, \P,D.v0o8.+KRsA<.,#c3XES`!W37F;bJYZr
xd%xcdd``dd``baV d,FYzP1n:&B@?b 20aꁪaM,,He`7S&,e`abM-VK-WMcZ>
X.d4+a|i_j_g<`~RaT f
+H? 0R,#%@W&0;b+800b8! v 0y{qĤ\Y\t0.?11d[@(
7Equation Equation.30,Microsoft Equation 3.008Equation Equation.30,Microsoft Equation 3.009Equation Equation.30,Microsoft Equation 3.0/0DTimes New Romant|dv0|(
0DArialNew Romant|dv0|(
0" DSymbolew Romant|dv0|(
0b&.
@n?" dd@ @@```Y?58 1Ee$$5
21$$$$$$e
367?2$<7DSiHx~>hP`2$}Pc_.(`m`PP`2$37F;bJYZ_`c$@uʚ;2Nʚ;g4;d;dv0pppp@<4!d!d`
0,`<4dddd`
0,`<4BdBd`
0,`2*___PPT9z'7DRecurrent Areas of Confusion in Student Learning of Thermodynamics EC$$David E. Meltzer
Department of Physics and Astronomy
and
Thomas J. Greenbowe
Department of Chemistry
Iowa State University
Ames, Iowa
Supported in part by National Science Foundation grant DUE #9981140\D ( $ !DC
~33ZStudents Evolving Concepts of ThermodynamicsMost students study thermodynamics in chemistry courses before they see it in physics
at Iowa State 90% of engineering students have taken chemistry before studying thermodynamics in their physics course
Ideas acquired in chemistry may impact learning in physics
Certain specific misconceptions regarding thermodynamics are widespread among chemistry studentsZVZxZ0Z<Vi +Conceptual Minefields Created in ChemistryThe state function enthalpy [H] comes to be identified in students minds with heat in general, which is not a state function.
[H = E + PV; DH = heat absorbed in constant-pressure process]
Contributions to DE due to work usually neglected; gas-phase reactions de-emphasized
The distinction between DH and DE is explicitly downplayed (due to small proportional difference)
Sign convention different from that most often used in physics: DE = Q + W (vs. DE = Q - W )
Z?!Z0Z<Z1
B
##!Results from Chemistry Diagnostic1 [Given in general chemistry course for science majors, Fall 2000, N =532]
65% of students recognized that change in internal energy was same for both processes.
Only 47% of students recognized that change in temperature must be the same for both processes (since initial and final states are identical).PL!XZZWPZsZJ54)Detailed Analysis of Sub-sample (N = 325)$*!11% gave correct or partially correct answer to work question based on first law of thermodynamics.
(10% had correct answer with incorrect explanation)
16% stated (about half because initial and final states are same ).
62% stated (almost half because internal energy is greater ).XsZ5!PZ<SPZ<MZs5,G6Physics DiagnosticGiven in second semester of calculus-based introductory course.
Traditional course; thermal physics comprised 20% of course coverage.
Diagnostic administered in last week of course:
Fall 1999: practice quiz during last recitation; N = 186
Fall 2000: practice quiz during final lecture; N = 188
Spring 2001: practice quiz during last recitation; N = 279
PZ<0ZZZs0233jSamples of Students Answers(All considered correct)6T DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
!@Kd!@2@2#;5!Conceptual Difficulties with WorkDifficulty interpreting work as area under the curve on a p-V diagram
Only 50% able to give correct explanation for W1 > W2
Belief that work done is independent of process
About 15-25% are under impression that work is (or behaves as) a state function.HZ:!Z00Z<R!Z< +0Q<6!Conceptual Difficulties with HeatBelief that heat absorbed is independent of process
About 20-25% of all students explicitly state belief that heat is path independent
Association of greater heat absorption with higher pressure (independent of complete process)
Use of compensation argument, i.e., more work implies less heat and vice versa.
Many students use argument without regard to DE
Some students use opposite sign convention, DE = Q + W
Others use correct sign convention, but make mathematical sign error4ZT!Z^pZi#T0ZF10Z~ Z4R^T,.P=7+Difficulty with First Law of ThermodynamicsOnly about 15% of all 645 students were able to give correct answer with correct (or partially correct) explanation based on first law of thermodynamics
very little variation semester to semester
Proportion of correct answers virtually identical to that found in chemistry courseFZ-!ZT0ZF-T>8Patterns Underlying ResponsesOf students who answer W1 = W2, about 50% incorrectly assert Q1 = Q2
Of students who correctly answer Work question (W1 > W2), about 35% also assert Q1 = Q2 FY
EZ?9@Justifications Given by Students Who Incorrectly Assert Q1 = Q2 6A9xStudents who answered Work question correctly usually claim heat is independent of path
Students who answered Work question incorrectly usually do not claim heat is independent of path TZc d.I$@:3Conjectures Regarding Dynamics of Student ReasoningBelief that heat is process-independent may not be strongly affected by realization that work is not process-independent.
Understanding process-dependence of work may strengthen mistaken belief that heat is independent of process.Bzm PakA;SummaryNo more than 15% of students are able to make effective use of first law of thermodynamics after introductory chemistry or introductory physics course.
Although similar errors regarding thermodynamics appear in thinking of both chemistry and physics students, possible links between conceptual problems need further study.
\Z0ZKZ
k""jSamples of Students Answers(All considered correct)6d DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
!PZsm!PZ2PZ2Z&)&&jSamples of Students Answers(All considered correct)6, DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
/!PZZa!PZ2!PZZ!PZ2PZ2Z&h)kB<mStudent Reasoning Regarding Work, Heat, and the First Law of Thermodynamics in an Introductory Physics CoursennvDavid E. Meltzer
Department of Physics and Astronomy
Iowa State University
Supported in part by NSF Grant DUE-9981140wL+ ` ̙33` ` ff3333f` 333MMM` f` f` 3>?" dd@&|?" dd@ " @ ` n?" dd@ @@``PR @ ` `p>>l(
6 P
T Click to edit Master title style!
!
0
RClick to edit Master text styles
Second level
Third level
Fourth level
Fifth level!
S
0 ``
@*
0 `
B*
0 `
B*
H
0h ? ̙33 Default DesignP @(
0 P
@*
0
B*
6p `P
@*
6С `
B*
H
0h ? ̙330$(
r
S
r
S@
H
0h ? ̙33
@($(
(r
( SAP
r
( SBP`
H
(0h ? ̙33
P<(
~
s*(IH8
~
s*IP `p
H
0h ? ̙33
`$(
r
S$P
r
S%
H
0h ? ̙33
p0\(
0r
0 SvP
r
0 Shw
`
0
c$A
??r
`
0
c$A?? }
`
0
c$A??Wz
_
H
00h ? ̙33
x$(
xr
x S
r
x St
H
x0h ? ̙33
$(
r
S
r
Sp
H
0h ? ̙33
8$(
8r
8 SP
r
8 S
H
80h ? ̙33
<$(
<r
< S]-
r
< S2Pxp
H
<0h ? ̙33J
@(
@r
@ SP
r
@ SD0
^
@
6 0$
H
@0h ? ̙33
D$(
Dr
D S|P
r
D S@`
H
D0h ? ̙33
H$(
Hr
H STP
r
H Sp
H
H0h ? ̙33
L$(
Lr
L SMP
r
L SN
H
L0h ? ̙33
P$(
Pr
P SP
r
P SP
H
P0h ? ̙33
0(
x
c$
x
c$@`
H
0h ? ̙33
0(
x
c$T
x
c$x
H
0h ? ̙33`\0(
\x
\ c$p0
x
\ c$ `
H
\0h ? ̙33xVkAf&&I-Z""-bHS4JSK*)FlֽI ^ozP$Eɫ=i5Mmو(|{O?'!Yƌ(nZkm6H:}?)8tUacE6]~~se^, r5YP,:fqi=P_ϙ17_7C)uG?\sM9~տ! D 1%tnso17ؾQK^cSqxi1[;E{$Rt6TzyJr_Gd+3w.ML*CjVfz{#]r8=Bآ_ۡFFOHP ]1'l괻@MnEq7ϩG|:_Utnɞr
"M|[Z%[) kr3T|_|uْî?Rr`MơyѰ9̴%O-:X:Emx uH12cTAsU^=gɸj 5[x{Lb{*O'mQF{HN1,Ɨsk!! bw8JXD*=O`>mNeV_Op%2wEzxVAkA~3fma ԋ`E#(MTҚd&5ݛT=Iċ>6h]#N:Byk6**hP`2$}Pc_.(`m`PP`2$37F;bJYZ_`c$@uʚ;2Nʚ;g4;d;dv0pppp@<4!d!d`
0,`<4dddd`
0,`<4BdBd`
0,`2*___PPT9zC7DRecurrent Areas of Confusion in Student Learning of Thermodynamics EC$$David E. Meltzer
Department of Physics and Astronomy
and
Thomas J. Greenbowe
Department of Chemistry
Iowa State University
Ames, Iowa
Supported in part by National Science Foundation grant DUE #9981140\D ( $ !DC
~33ZStudents Evolving Concepts of ThermodynamicsMost students study thermodynamics in chemistry courses before they see it in physics
at Iowa State 90% of engineering students have taken chemistry before studying thermodynamics in their physics course
Ideas acquired in chemistry may impact learning in physics
Certain specific misconceptions regarding thermodynamics are widespread among chemistry studentsZVZxZ0Z<Vi +Conceptual Minefields Created in ChemistryThe state function enthalpy [H] comes to be identified in students minds with heat in general, which is not a state function.
[H = E + PV; DH = heat absorbed in constant-pressure process]
Contributions to DE due to work usually neglected; gas-phase reactions de-emphasized
The distinction between DH and DE is explicitly downplayed (due to small proportional difference)
Sign convention different from that most often used in physics: DE = Q + W (vs. DE = Q - W )
Z?!Z0Z<Z1
B
##!Results from Chemistry Diagnostic1 [Given in general chemistry course for science majors, Fall 2000, N =532]
65% of students recognized that change in internal energy was same for both processes.
Only 47% of students recognized that change in temperature must be the same for both processes (since initial and final states are identical).PL!XZZWPZsZJ54)Detailed Analysis of Sub-sample (N = 325)$*!11% gave correct or partially correct answer to work question based on first law of thermodynamics.
(10% had correct answer with incorrect explanation)
16% stated (about half because initial and final states are same ).
62% stated (almost half because internal energy is greater ).XsZ5!PZ<SPZ<MZs5,G6Physics DiagnosticGiven in second semester of calculus-based introductory course.
Traditional course; thermal physics comprised 20% of course coverage.
Diagnostic administered in last week of course:
Fall 1999: practice quiz during last recitation; N = 186
Fall 2000: practice quiz during final lecture; N = 188
Spring 2001: practice quiz during last recitation; N = 279
PZ<0ZZZs0233jSamples of Students Answers(All considered correct)6T DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
!@Kd!@2@2#;5!Conceptual Difficulties with WorkDifficulty interpreting work as area under the curve on a p-V diagram
Only 50% able to give correct explanation for W1 > W2
Belief that work done is independent of process
About 15-25% are under impression that work is (or behaves as) a state function.HZ:!Z00Z<R!Z< +0Q<6!Conceptual Difficulties with HeatBelief that heat absorbed is independent of process
About 20-25% of all students explicitly state belief that heat is path independent
Association of greater heat absorption with higher pressure (independent of complete process)
Use of compensation argument, i.e., more work implies less heat and vice versa.
Many students use argument without regard to DE
Some students use opposite sign convention, DE = Q + W
Others use correct sign convention, but make mathematical sign error4ZT!Z^pZi#T
!"#$%&'()*+,-./0123456789:;<=>?@ABCD`FGIJKLMNOPQRSTUVWXYZ[\_abcdefghijklmnopqrstuvwxyz{|}~Root EntrydO)@h%PicturesCurrent UserJPSummaryInformation(
PowerPoint Document(;DocumentSummaryInformation87quation Equation.30,Microsoft Equation 3.009Equation Equation.30,Microsoft Equation 3.0/00DTimes New Romant|dv0|(
0DArialNew Romant|dv0|(
0" DSymbolew Romant|dv0|(
00DCourier Newmant|dv0|(
01b&.
@n?" dd@ @@``dZ?58 1Ee$$5
21$$$$$$e
3678?2$<7DSiHx~>hP`2$}Pc_.(`m`PP`2$37F;bJYZ_`c$@uʚ;2Nʚ;g4;d;dv0pppp@<4!d!d`
0,`<4dddd`
0,`<4BdBd`
0,`2*___PPT9zC7DRecurrent Areas of Confusion in Student Learning of Thermodynamics EC$$David E. Meltzer
Department of Physics and Astronomy
and
Thomas J. Greenbowe
Department of Chemistry
Iowa State University
Ames, Iowa
Supported in part by National Science Foundation grant DUE #9981140\D ( $ !DC
~33ZStudents Evolving Concepts of ThermodynamicsMost students study thermodynamics in chemistry courses before they see it in physics
at Iowa State 90% of engineering students have taken chemistry before studying thermodynamics in their physics course
Ideas acquired in chemistry may impact learning in physics
Certain specific misconceptions regarding thermodynamics are widespread among chemistry studentsZVZxZ0Z<Vi +Conceptual Minefields Created in ChemistryThe state function enthalpy [H] comes to be identified in students minds with heat in general, which is not a state function.
[H = E + PV; DH = heat absorbed in constant-pressure process]
Contributions to DE due to work usually neglected; gas-phase reactions de-emphasized
The distinction between DH and DE is explicitly downplayed (due to small proportional difference)
Sign convention different from that most often used in physics: DE = Q + W (vs. DE = Q - W )
Z?!Z0Z<Z1
B
##!Results from Chemistry Diagnostic1 [Given in general chemistry course for science majors, Fall 2000, N =532]
65% of students recognized that change in internal energy was same for both processes.
Only 47% of students recognized that change in temperature must be the same for both processes (since initial and final states are identical).PL!XZZWPZsZJ54)Detailed Analysis of Sub-sample (N = 325)$*!11% gave correct or partially correct answer to work question based on first law of thermodynamics.
(10% had correct answer with incorrect explanation)
16% stated (about half because initial and final states are same ).
62% stated (almost half because internal energy is greater ).XsZ5!PZ<SPZ<MZs5,G6Physics DiagnosticGiven in second semester of calculus-based introductory course.
Traditional course; thermal physics comprised 20% of course coverage.
Diagnostic administered in last week of course:
Fall 1999: practice quiz during last recitation; N = 186
Fall 2000: practice quiz during final lecture; N = 188
Spring 2001: practice quiz during last recitation; N = 279
PZ<0ZZZs0233jSamples of Students Answers(All considered correct)6T DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
!@Kd!@2@2#;5!Conceptual Difficulties with WorkDifficulty interpreting work as area under the curve on a p-V diagram
Only 50% able to give correct explanation for W1 > W2
Belief that work done is independent of process
About 15-25% are under impression that work is (or behaves as) a state function.HZ:!Z00Z<R!Z< +0Q<6!Conceptual Difficulties with HeatBelief that heat absorbed is independent of process
About 20-25% of all students explicitly state belief that heat is path independent
Association of greater heat absorption with higher pressure (independent of complete process)
Use of compensation argument, i.e., more work implies less heat and vice versa.
Many students use argument without regard to DE
Some students use opposite sign convention, DE = Q + W
Others use correct sign convention, but make mathematical sign error4ZT!Z^pZi#T0ZF10Z~ Z4R^T,.P=7+Difficulty with First Law of ThermodynamicsOnly about 15% of all 645 students were able to give correct answer with correct (or partially correct) explanation based on first law of thermodynamics
very little variation semester to semester
Proportion of correct answers virtually identical to that found in chemistry courseFZ-!ZT0ZF-T>8Patterns Underlying ResponsesOf students who answer W1 = W2, about 50% incorrectly assert Q1 = Q2
Of students who correctly answer Work question (W1 > W2), about 35% also assert Q1 = Q2 FY
EZ?9@Justifications Given by Students Who Incorrectly Assert Q1 = Q2 6A9xStudents who answered Work question correctly usually claim heat is independent of path
Students who answered Work question incorrectly usually do not claim heat is independent of path TZc d.I$@:3Conjectures Regarding Dynamics of Student ReasoningBelief that heat is process-independent may not be strongly affected by realization that work is not process-independent.
Understanding process-dependence of work may strengthen mistaken belief that heat is independent of process.Bzm PakA;SummaryNo more than 15% of students are able to make effective use of first law of thermodynamics after introductory chemistry or introductory physics course.
Although similar errors regarding thermodynamics appear in thinking of both chemistry and physics students, possible links between conceptual problems need further study.
\Z0ZKZ
k""jSamples of Students Answers(All considered correct)6d DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
!PZsm!PZ2PZ2Z&)&&jSamples of Students Answers(All considered correct)6, DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
/!PZZa!PZ2!PZZ!PZ2PZ2Z&h)kB<mStudent Reasoning Regarding Work, Heat, and the First Law of Thermodynamics in an Introductory Physics CoursennvDavid E. Meltzer
Department of Physics and Astronomy
Iowa State University
Supported in part by NSF Grant DUE-9981140wL+C=H HEd(
dP
d
6ҟ\TL___PPT9.&
DThis material is based upon work supported by the National Science Foundation under Grant Number DUE-9981140.
REFERENCES
M.E. Loverude, P.R.L. Heron, and C.H. Kautz, "Student understanding of the first law of thermodynamics: Relating work to the adiabatic compression of an ideal gas," Phys. Educ. Res., Am. J. Phys. Suppl. (to be published).
2. D.E. Meltzer and T.J. Greenbowe, Recurrent areas of confusion in student learning of thermodynamics, AAPT Announcer 31(2), 81 (2001).
3. R.K. Thornton, Conceptual Dynamics: fol-lowing changing student views of force and mo-tion, in AIP Conf. Proc. 399, E.F. Redish and J.S. Rigden, eds. (AIP, N.Y., 1997), pp. 241-266.
L|Gp#######y####t##!####n .
/ ( @`H
d0h ? ̙33rxC=
xGCA(
7
!"#$%&'()*+,-./012345689:;<=>?@ABCDEFGHIKOh+'0p
hp
PowerPoint PresentationoweoweDavid E. Meltzertat191Microsoft PowerPointon@P'9@@`h%GJ g&U &&#TNPPL2OMi
&
TNPP &&TNPPU
--- !U---&?Fs&/gw@
IwIw0- &"F3s& --:@$-- @"Arialw@A
5IwIw0- .72
Rf Recurrent Areas of Confusion in . .<2
.#Student Learning of Thermodynamics &&.--l9-- @"Arialw@R
IwIw0- .2
David E. Meltzer
.@"Arialw@A
8IwIw0- .<2
#Department of Physics and Astronomy
.@"Arialw@R
IwIw0- .2
Jand8.@"Arialw@A
8Patterns Underlying ResponsesOf students who answer W1 = W2, about 50% incorrectly assert Q1 = Q2
Of students who correctly answer Work question (W1 > W2), about 35% also assert Q1 = Q2 FY
EZ?9@Justifications Given by Students Who Incorrectly Assert Q1 = Q2 6A9xStudents who answered Work question correctly usually claim heat is independent of path
Students who answered Work question incorrectly usually do not claim heat is independent of path TZc d.I$@:3Conjectures Regarding Dynamics of Student ReasoningBelief that heat is process-independent may not be strongly affected by realization that work is not process-independent.
Understanding process-dependence of work may strengthen mistaken belief that heat is independent of process.Bzm PakA;SummaryNo more than 15% of students are able to make effective use of first law of thermodynamics after introductory chemistry or introductory physics course.
Although similar errors regarding thermodynamics appear in thinking of both chemistry and physics students, possible links between conceptual problems need further study.
\Z0ZKZ
k""jSamples of Students Answers(All considered correct)6d DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
!PZsm!PZ2PZ2Z&)&&jSamples of Students Answers(All considered correct)6, DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
E = Q W, Q = E + W, if E is the same and W is greater then Q is greater for Process #1.
/!PZZa!PZ2!PZZ!PZ2PZ2Z&h)kB<mStudent Reasoning Regarding Work, Heat, and the First Law of Thermodynamics in an Introductory Physics CoursennvDavid E. Meltzer
Department of Physics and Astronomy
Iowa State University
Supported in part by NSF Grant DUE-9981140wL+C=r=
_C6(
7Equation Equation.30,Microsoft Equation 3.008Equation Equation.30,Microsoft Equation 3.009Equation Equation.30,Microsoft Equation 3.0/00DTimes New Romant|dv0|(
0DArialNew Romant|dv0|(
0" DSymbolew Romant|dv0|(
00DCourier Newmant|dv0|(
01b&.
@n?" dd@ @@``hZ?8Ee$$
1$$$$$$e
37?2$<7DSiHx~>hP2$}Pc_.(`m`PP2$37F;bJYZ_c$@uʚ;2Nʚ;g4;d;dv0pppp@<4!d!d`
0,`<4dddd`
0,`<4BdBd`
0,`2*___PPT9z-DRecurrent Areas of Confusion in Student Learning of Thermodynamics EC$$David E. Meltzer
Department of Physics and Astronomy
and
Thomas J. Greenbowe
Department of Chemistry
Iowa State University
Ames, Iowa
Supported in part by National Science Foundation grant DUE #9981140\D ( $ !DC
~33ZStudents Evolving Concepts of ThermodynamicsMost students study thermodynamics in chemistry courses before they see it in physics
at Iowa State 90% of engineering students have taken chemistry before studying thermodynamics in their physics course
Ideas acquired in chemistry may impact learning in physics
Certain specific misconceptions regarding thermodynamics are widespread among chemistry studentsZVZxZ0Z<Vi +Conceptual Minefields Created in ChemistryThe state function enthalpy [H] comes to be identified in students minds with heat in general, which is not a state function.
[H = E + PV; DH = heat absorbed in constant-pressure process]
Contributions to DE due to work usually neglected; gas-phase reactions de-emphasized
The distinction between DH and DE is explicitly downplayed (due to small proportional difference)
Sign convention different from that most often used in physics: DE = Q + W (vs. DE = Q - W )
Z?!Z0Z<Z1
B
##!Results from Chemistry Diagnostic1 [Given in general chemistry course for science majors, Fall 2000, N =532]
65% of students recognized that change in internal energy was same for both processes.
Only 47% of students recognized that change in temperature must be the same for both processes (since initial and final states are identical).PL!XZZWPZsZJ54)Detailed Analysis of Sub-sample (N = 325)$*!11% gave correct or partially correct answer to work question based on first law of thermodynamics.
(10% had correct answer with incorrect explanation)
16% stated (about half because initial and final states are same ).
62% stated (almost half because internal energy is greater ).XsZ5!PZ<SPZ<MZs5,G6Physics DiagnosticGiven in second semester of calculus-based introductory course.
Traditional course; thermal physics comprised 20% of course coverage.
Diagnostic administered in last week of course:
Fall 1999: practice quiz during last recitation; N = 186
Fall 2000: practice quiz during final lecture; N = 188
Spring 2001: practice quiz during last recitation; N = 279
PZ<0ZZZs0233""jSamples of Students Answers(All considered correct)6d DE = Q W. For the same DE, the system with more work done must have more Q input so process #1 is greater.
Q is greater for process 1 since Q = E + W and W is greater for process 1.
Q is greater for process one because it does more work, the energy to do this work comes from the Qin.
!PZsm!PZ2PZ2Z&);5!Conceptual Difficulties with WorkDifficulty interpreting work as area under the curve on a p-V diagram
Only 50% able to give correct explanation for W1 > W2
Belief that work done is independent of process
About 15-25% are under impression that work is (or behaves as) a state function.HZ:!Z00Z<R!Z< +0Q<6!Conceptual Difficulties with HeatBelief that heat absorbed is independent of process
About 20-25% of all students explicitly state belief that heat is path independent
Association of greater heat absorption with higher pressure (independent of complete process)
Use of compensation argument, i.e., more work implies less heat and vice versa.
Many students use argument without regard to DE
Some students use opposite sign convention, DE = Q + W
Others use correct sign convention, but make mathematical sign error4ZT!Z^pZi#T0ZF10Z~ Z4R^T,.P=7+Difficulty with First Law of ThermodynamicsOnly about 15% of all 645 students were able to give correct answer with correct (or partially correct) explanation based on first law of thermodynamics
very little variation semester to semester
Proportion of correct answers virtually identical to that found in chemistry courseFZ-!ZT0ZF-T>8Patterns Underlying ResponsesOf students who answer W1 = W2, about 50% incorrectly assert Q1 = Q2
Of students who correctly answer Work question (W1 > W2), about 35% also assert Q1 = Q2 FY
EZ?9@Justifications Given by Students Who Incorrectly Assert Q1 = Q2 6A9xStudents who answered Work question correctly usually claim heat is independent of path
Students who answered Work question incorrectly usually do not claim heat is independent of path TZc d.I$@:3Conjectures Regarding Dynamics of Student ReasoningBelief that heat is process-independent may not be strongly affected by realization that work is not process-independent.
Understanding process-dependence of work may strengthen mistaken belief that heat is independent of process.Bzm PakA;SummaryNo more than 15% of students are able to make effective use of first law of thermodynamics after introductory chemistry or introductory physics course.
Although similar errors regarding thermodynamics appear in thinking of both chemistry and physics students, possible links between conceptual problems need further study.
\Z0ZKZ
kr;
;Ct**