Physics, an Important Factor in the Success of General College Chemistry Students Sidney P. Harris Queens College of the City University of New York. Flushing, NY 11367 Scholastic background and entrance requirements were once used as reasonable guides in predicting performance in future courses. In recent years, many schools have relaxed their entrance requirements and thus it is often difficult for instructors to predict the future academic progress of their students. In an effort to find out more about students in our first year colleee chemistrv course, a questionnaire was distributed during the first l&ture. The students were asked to give their oreviuus ~ r e ~ a r a t i oinn chemistry, physirs and mathematics at both secondary and college levels and to state their career plans. The responses of 1008 students were then compared to their performance in the first year course. The results of this study are presented below.
Table 1. CornporHe Reruns Number of Succesld Students
Total Number
Stdents in this WWW
of
( B or
bener)
Secandar,
Scbl
Preparation
Percent Suecess
1 y. Chem.
and 380 4
Totals
RR
624 5 379
452
1008
1 p.Physics 1 y. Physics (only) 1 w. Chem. lonlv)
60.9 80.0 17.9 44.8
Preliminary Analysis Over the 10 years that this questionnaire has been used all but three students were found to have taken at least three years of secondary school mathematics. Many students seem deficient in their knowledge of logarithms, hut in general scientific calculators help solve the manipulative problems. However, in general, students have sufficient basic mathematics . ~ r e.~ a r a t i oton he successful in the general college chemistry course. In the final erade distribution, success in the class was defined as recei;ing a grade of B- or better. No scaling (or curving) was used, only the highest 10 of 12 weekly examinations were considered. The laboratory grades were given as 10,8.5,7, and 5 with a grade of 10 meaning that there were no major errors and at most, two minor errors.
Table 1shows that 62.4% of all students in the group had taken a t least one year of physics in secondary school, or in a few cases, college physics. Better than Zl6 of these students were successful (with a grade of 78% or better). On the other hand, only about 'I6 of the students who had no physics preparation were similarly successful. Forty percent of the students with previous preparation in physics were unsuccessful in this course. An examination of the student questionnaires showed that about half planned majors in fields including geology, physics, and engineering, excluding chemical engineering. Of murse, the student.? in any of the test groups may have later changed their career plans. One explanation for the lack of success of these unsuccessful students is that their prior science courses may have been memory-oriented.' Our course is quantitative and requires understanding.
Paper delivered before the Division of Chemical Education at the 182nd ACS National Meeting. New York. August 23. 1981. ' Kovacic. P. and Jones, M. 6.. J. College Sci. Tchg.. 11, 356 (1982). CfaITlor, H.. "The Elements of Robability Theoly." John Wiby. New York. 1955, pp. 171. 205. 256.
Statistical Data There were 101 students who were in the author's lecture, recitation. and laboratow classes. Numerical equivalents were assigned k, t hew stude& in an effort t o s ~ t i s l i ~ aP lVl ~H ~ U R their success in relation to thrir high schuul prepar~tionin chemistry and physics. A group of 40 studentswho had com-
Volume 60
Number 9
September 1983
739
~ ~
Table 2.
A
StatlMlcal Comparison of the Two Groups 0140 Students ChemlsW and Physics Preparation
Stendad Deviation. o
79.00% 9.19
Variance, a2
84.5
man
Range of Numerical Orades N u m b ot Grades,8- w greater
9656 28
Only Chemistry Preparation
63.25% 13.02 170
98-29 4
pleted high school chemistry and physics was chosen a t random and coded P. These students were statistically compared to an eaual number who lacked . prior phvsics oreoaration and . . . were coded C. Table 2summarizes the results obtained from the P a n d C groups of students. The mean grade, first assumed to he the same for these two groups, was found to be significantly different. In fact, the P group of students was almost two standard deviations above the C group. The n - 1 factor in the denominator of the standard error expression (a/-) means that there are 39 degrees of freedom for each group of students or 78 degrees of freedom for the sample. Since the standard deviations are not the same, a pooled value must be determined.2 The pooled standard deviation, a, is 15.94. The square of the n value is the variance. Sim~larly, a pooled standard error. 4. is required. ~
~
0.. =
(2)
The squares of the standard error terms under the radical are the terms for the more able P group and for the less able C group of students. The pooled standard error was thus determined to be 2.55. The difference between the two means divided by the pooled standard error is represented by t. t = (F - C)/Ae (3)
t = 6.18
are taught in the general college chemistry curriculum and secondary school physics classes. Physics typically includes a study of the ideas of atomic structure, i.e., the work of J. J. Thomson in the determination of the chareelmass ratio for the electron; the work of R. A. Millikan in tce determination of the charge on the electron and the resulting rest mass of the electron; and E. Rutherford's work in developing a model of the atom and its dimensions. Atomic numbers, the Bohr atom, the quantitative characterization of electromagnetic radiation, line spectra and quantum theory are all fundamental to the development of most secondary school physics classes. These tooics and understandines built upon them are incIuded in thk curriculum of collegechemistry courses. In the topic, reaction kinetics, the student who understands Coulomb's Law (from physics) can readily determine the slowest step in a mechanism involving like-charged ions. Electrochemistry is seldom troublesome for students who have been introduced previously to coulombs, amperes, volts, and joules. A physics background has proven to he important in our course in the ore-laboratorv assienments which are done hv the student hifore the lab periody3 For example: in an experof the tri-oxalato iment involvine.. the ~hoto-decomoosition . ferrate(II1Jion: the pre.lata,ratory assignment involved the determination of whether it is oossihle tu break the bonds in Brz(g), a red-orange vapor, using a source of photons having a frequency of 7 X 10IVsec.The region of the visible spectrum in which absorption takes place was also required. This material in color absorption and quantum theory can only be fully appreciated by a student with an excellent background in modern physics. We feel that approximately 20% of the course in general college chemistry is dependent upon some concepts having an origin in physics. Conclusion The results show that most well-prepared students do well in " eeneral colleee is defined as " chemistrv. - (Well-ureoared . having had previous preparation in chemistry, physics, and mathematics.) The general college chemistry curriculum includes a vast amount of secondary school physics. Unfortunatelv. .. the hackeround in .nhvsics . that manv students lack is often assumed to he present.
. .
-
This result substantiates a t better than the 99.9% confidence level, the finding that there is a significant difference between these two groups. Explanation
We believe that une reason for the significant difference results from the appreciahle number of similar topirs which
Baker. A. D.. Gries. L. F.. and Navidi. M. H., "Experiments for Introductory Chemistry." 3rd Ed.. Avery, Wayne, NJ, p. 197. 58, 655. (1981). Vitz. E. W.. J. CHEM.EDUC.,
Penny Infrared Cells for Water Solutions Coin holders used by collectors are now often made with polyethylene linings instead of polystyrene, end this material. because of its few absorption bands in the infrared, is a superior support for aqueous solutions as well as other liquids. At about $1.50 per hundred these cells are nearly a penny apiece, and the size (2 X 2 in.) is just right for most commercial spectmphotometercell holders. Against a reference cell composed of an empty coin holder (preferablynickel size) very goad spectra cam be obtained. Of course, the sides of the cell should be taped and stapled to prevent leakage;the sample is introduced at the top with a medicine dropper and the cell automatically squeezes it to a fairly uniform film. J. P. Phillips
University of Louisville Louisville. KY 40292
740
Journal of Chemical Education
