NOTE TO TEACHERS/STUDENTS
A highly respected
school in New Zealand used an early version of this calculator extensively.
The students could solve worksheet problems and then check their answer
without the intimidation of a teacher or fellow student.
The teachers used this calculator to create tests and worksheets. Even
the lab technicians used the calculator to create chemical solutions.
The student is encouraged to learn the basic relationship
among chemistry quantities for the calculator to make sense. When doing
homework, to prevent a student from "cheating" by just reading the
answer, the teacher should require them to show the "setup" of the
problem. In other words, they should show what quantities are
multiplied, divided, etc. They can then calculate the answer by hand
and compare their answer against the spreadsheet calculator. As an
additional benefit, the
spreadsheet shows a lot of intermediate results to help the student
find any problems in their calculations.
The relationship among the entries in the spreadsheet are easy to understand.
Once the equation is balanced, a single entry for moles or grams of a chemical
allows the spreadsheet to calculate all the other values of moles and grams
for all the chemicals in the equation. Then if you are working with a solution,
you simply supply the volume of that solution to calculate the Molarity in
moles per liter. There are variations on this relationship. Any two of the
variables (moles,liters,moles/liter) allows the third to be calculated.
If you supply too much information such as supplying moles, liters, and
moles/liter, the calculator may still accept the data if it is basically
correct or it may flag a contradiction error if the values are too far off.
Ideal gases tie together liters and moles on the first sheet to pressure
and temperature on the GASES sheet using the equation PV=nRT. Once again,
supplying any three of the four variables results in the fourth variable
being solved. The idea of the spreadsheet is to derive as many values as
possible given the input data. A student may discover they have not supplied
enough data to get an answer.
You should watch out for only one thing. If you are using a solution, the
grams column represents the mass of chemical disolved in the solution and
not the actual weight of the solution. Generally you use volume or liters
to measure a liquid solution so there is no problem here.
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