Calculators for Chemists were set up as calculators of course but also for the following didactical reasons:
- to present a molar mass calculator demonstrating how the calculation of the molar mass is done
- as a summary of some elementary quantitative mathematical formulas used by chemists
- to present a course where the formulas are given in a logical order and the formulas with the molar mass are at the last positions because these are less important than the other formulas with the for all chemistry central concept, the amount of substance
- for the implementation of a Java Script, written for the reason of a good treatment of significant digits in calculations with measured values, as explained below
Calculators for Chemists work this way:
- the known quantities are entered leaving one field blank
- the significant digits in these quantities are counted
- the unknown quantity is calculated
- the unknown quantity is presented with as many significant digits as in the least count of significant digits in the known quantities
Calculations with measured quantities are not exact. The sign of equality is conventionally used although both sides of it are not equal, mathematically speaking. Calculation with one significant digit as an example gives 2 * 5 = 3 * 3 and this may seem a bit odd if the concept of significant digits are not fully understood. The Significant Digits Counter explains the rules used when the significant digits are counted.
An important part of this work has been the development of the Java Script that counts the significant digits in the known quantities and formats the results of the calculations with a given number of significant digits. It may be downloaded and used in other applications of a similar kind.
If you like this site you may also like other publications by the same author at Chemistry for Free.