Calculators for Chemists

About Calculators for Chemists

Calculators for Chemists were set up as calculators of course but also for the following didactical reasons:

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.