McDalton
Mass calculator Dalton
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These programs, for calculation of molar or formula masses, were developed because none among a lot of freeware or shareware programs of the same kind fits the qualifications listed below. There are two editions of McDalton.
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McDalton Learning Edition 1.0 (Latest release published in January 2008)
Most textbooks include an atomic mass table with values rounded to one or two decimals. For compatibility with answers on examples given in those textbooks McDalton Learning Edition includes the option to use a fixed number of decimals. This may also increase the readability of the output. On recommendation by The International Union of Pure and Applied Chemistry, IUPAC, atomic weights of the elements are taken from the review Atomic weights of the elements 2007, published in Pure Appl. Chem. 78(11), 2051-2066, 2006 and Aug 2007 release. As default all figures are used in the calculations. If you enter the formula of just one element the recommended atomic weight is displayed. This program is certified by Softpedia and has the author's digital signature. It is safe to download. |
This is a freeware computer program, designed for learning purposes, to calculate molar or formula masses. For this reason the calculations are shown together with the result.
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McDalton Professional Edition 1.0 (Latest release published in January 2008) This is a freeware computer program, designed for professional use. In this program the uncertainty in the calculated molar mass is given as the absolute maximum error of the result. The calculated uncertainty is always rounded up to one significant figure. It is rounded up because otherwise it may occur as underestimated. Then the molar mass is rounded to the same absolute accuracy as given in the rounded uncertainty.
On recommendation by The International Union of Pure and Applied Chemistry, IUPAC, atomic weights of the elements are taken from the review Atomic weights of the elements 2007, published in Pure Appl. Chem. 78(11), 2051-2066, 2006 and Aug 2007 release. As default all figures are used in the calculations. If you enter the formula of just one element the recommended atomic weight is displayed. In this Professional Edition the calculations are shown if the mouse is paused over the values. |
An example will make this clear. The molar mass for PbO is calculated as 207.2 + 15.9994 = 223.1994 and the uncertainty in the molar mass is calculated as 0.1 + 0.0003 = 0.1003. The only significant figure in the uncertainty is the first decimal and therefore molar mass is given as 223.2 ± 0.2 which is the best value and of course the uncertainty is rounded up as explained before.|
Download These programs are developed with Visual Basic 6.0 and made for the Windows operating system.
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Handbook
About these programs
In these programs there are not drawn up any special rules for typing chemical formulas. Just type them as you normally do. Nothing extra to learn and remember. This is made clear by examples in the McDalton Learning Edition program window shown on this page.
The McDalton Professional Edition is the only program, or maybe one of a few programs of this kind, that is able to calculate molar mass of a substance like sodiumiron(III)sulfate, 3Na2SO4·Fe2(SO4)3·6H2O.
A propagation of error analysis of the result is always made and the mass is then rounded to a plausible number of significant figures. In the Professional Edition the absolute maximum error of the result is displayed. In this edition the calculations is shown if the mouse is paused over the values. In the Learning Edition rounded masses are displayed if "Best round off result" is selected from the menu.
According to international conventions and for learning purposes chemical formulas are formatted like CuSO4·5H2O and not like CuSO4*5H2O as in many other applications.
In the Learning Edition leading numbers like 2Na are not allowed. This is because students often tend to include coefficients from chemical reaction formulas in their calculations. This may lead to difficulties in their studies later on. There is no limitations of this kind in the Professional Edition because a few chemical formulas actually begin with a number.
For security and learning purposes elements must be entered in proper capitalisation. For example Co means Cobalt while CO means Carbon and Oxygen.
These programs are named after John Dalton, the founder of modern atomic theory. He was born on September 6, 1766 in Eaglesfield, England. The atomic theory was based on works on mass and chemistry done by Dalton, Proust and Lavoisier.
You will find information and more applications by the same author at www.chem4free.info