# Using MathCAD In High School and Freshman Chemistry

Author(s):

M. Gwen Sibert
Roanoke Valley Governor's School for Science and Technology
Roanoke, VA

The chemistry course at the Governor's School is taken primarily by juniors, and some of the sophomores who enter the school as ninth, rather than tenth graders. The course itself is not high school chemistry, nor is it AP chemistry, rather it is like freshman college chemistry. The textbook currently used is General Chemistry, Third Edition, by McQuarrie and Rock.

The calculus course at the Governor's school uses Math CAD for Macintosh, and there is limited use of it in the precalculus course. Because most of the chemistry students are in precalculus or calculus it is only natural that MathCAD be used by students taking chemistry.

I decided that the best, and simplest way to introduce MathCAD in the chemistry course was to have the students first use it to solve an equation, and then a couple of weeks later progress to graphing Beer's Law and kinetics data. I decided that the Rydburg-Balmer equation would be a great place to start. The students had just finished an activity in which they had observed the line spectra for several elements using spectrum tubes and hand-held spectroscopes. They used a spreadsheet to calculate the frequencies and energies of the lines they had seen, and until last year they had also used the spreadsheet to solve the Rydburg-Balmer equation for the initial energy level of the hydrogen electrons. Most of the students were eventually successful, but it took several attempts to get the equation entered correctly, because all the nested parentheses that were needed to get the operations grouped correctly.

It was at this point last year that I participated in a workshop on MathCAD for the science faculty which was presented by our math faculty. I used the Rydburg-Balmer equation to practice my newly learned skills and was very impressed with the software and the appearance of the final product. Math CAD allows you to type out the equation the way it appears on paper. It is easy
to enter text to define variables and constants and any other descriptions that might be desired. All of the Greek symbols are also supported, a feature I think is very important.

The class meets in the computer lab the day I introduce the students to MathCAD so that each student can work
The graphing assignment is coming soon, but I have changed it from what was done last year. That assignment was for the students to set up templates to graph Cone. vs time, In Cone. vs time, and 1/Conc vs time for five sets of kinetics data. Then for the equation that showed a straight line they were to determine the order, the rate, and the rate constant for each set. This year they will have only one of this type of problem. Thewill also be asked to graph V IT = k and PV = k, where is k is a constant, using a minimum of 5 points for each. In addition, they will be given In P =A- dHvapiRT and values for vapor pressure and temp and determine the value of dHv811. Lastly, they will be given solution concentrations in molality and boiling points and after graphing cone. vs b.p., determine the slope to obtain Kb. I had my classes do this assignment on Kaleidagraph for several years to help them learn that graphing software, but since almost all of them are quite proficient at it when they come into chemistry, this seems like an excellent way to provide experience in graphing with MathCAD.

The specific directions that are given out to the students pertainingto MathCAD itself and the assignment details can be viewed at the website given above. I want to acknowledge the help of the math faculty at the Governor's School who showed me how to use Math CAD and who developed the student directions for the various assignments. Thanks go to Julie Taibbi, Susan Kennedy, John Cannaday, and Ken Weddle.

Date:
03/06/96 to 03/10/96