JOURNRL OF
Chemical € ducation: Software Abstracts for Volume 6B, Number 2 KinWORKS: A Learning Tool for Kinetics Lab Richard W. Rarnette ~ a r k o College n Northfiled, MN 55057
KinWORKS is a computer simulation that is designed to help students learn how to design chemical kinetics experiments, collect and analyze kinetic data, and draw conclusions from those data. I t offers a large number of reactions of graded complexity to investigate. provides far the instructor to make unique assignments for each student, including assignments where the solutions are not revealed. Solutions to these reactions can he revealed thmugh use of an auxiliary program. reouires the student to desien even, exveriment to ahtain time and wncentrstux data. 'I'hls mvnl\~esselectwn of ternprmtLre, ingttnl concentrations, whether to use rhe ~ n l c k ~ u t t drare law mrthod or m>rlal rare* mrthwl, and when the data points are taken as the reaction progresses. imposes experimental error on all data, which results in a data-quality penalty for poorly designed experiments. Examples are inadequate flooding, failure to let the reaction progress far enough for integrated rate law work, or attempting to deduce the activation energy by using a temperature range that is toa small. includes convenient high-resolution platting. Any or all reaetant concentrations from the data sets may he plotted versus time a s either concentration, reciprocal concentration, or natural logarithm of concentration. Aleast squares fit of the data is shown with each plat. nermits simulation of realistic data far a known reaction
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printed problems based on actual reactions. permits graphical analysis of externally prepared data, such as actual laboratory data, literature data, or textbook pmblems. This feature includes time and concentration data, which can he plotted as described above, and temperature and rate constant data. which can he dotted in wavs . aovra., prrate to drrerminmy ;he ncrivauun i n e r g \ . Such dotn can br enrrrrd dmrtly into KmWORKS or retnevrd from files prepared by a text editor. provides an efficient, friendly interface with both keyboard and mouse support that makes it easy to carry out a number of experiments in a short time and safeguards against user averation errors. .offers on-screen helpon kinetics principles and experimental strategy, with calculation examples.
KinWORKS organizes reactions into three levels of stoichiometric complexity: easiest
A hardest
+ ... + bB pP+ ... + bB + eC + pP+ . .
A +pP A
where b, c and p are integer stoichiornetric coefficients. Each reaction is given a unlaue set of characteristics. The stoichiometrie co&icients are known, but not the rate constant, activation energy, or the reaction orders. KinWORICS sets up a standard type of rate law for each reaction: 762
Journal of Chemical Education
rate = 4 I A l l d t = dlPllpdt = k LAI*IBt"IClZ
Generally, the orders for reactants x, y, and z may be 0,1 or 2. However, experienced users can challenge themselves with problems where z may be from -2 to +2 and may be fractional.
Quantum Barrier David A. Lloyd
Hofstra University Hempstead, NY 11550 The interaction of a quantum mechanical particle with a ~otentialenerw barrier illustrates a number of interesting aspects of quantum behavior, the best known of which is tunneling. This problem has been treated in quantum mechanics texts by Pilar (l),Atkins(Z),Davis (31,and Powell and Craseman (4).There is excellent software by Rioux ( 5 ) available for many bound-state quantum mechanics problems, hut it does not include the barrier problem. Quantum Barrier allows students to interactively discover the effect of particle energy, particle current, barrier height, and bamer thickness on the reflection and transmission coefficients.At the same time the wave function for the particle beam is displayed. The Quantum Bamer display screen consists of three panels. The lower, or control panel, allows the student to try particle energies up to 1000 eV in 1%increments, and barrier energies up to 400 eV in 5% increments. Thus, the ratio of particle energy to bamer height can be adjusted from 0.025 to 50. The barrier width can be changed from 0.2 to 2.0 Angstrom units, and the particle beam current is
