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Turnbull China Bikeride
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Turnbull China Bikeride - Disc 2.iso
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AVOGADRO
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CHEMISTRY
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MOLWEIGHT
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!MolWeight
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1996-01-01
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Information is available on:
The Main MolWeight Window
Entering Molecular Formulae
Exact Isotopes
Editing Atomic Data
Entering Group Data
_______________________________________
Note that if any read me files are
supplied as part of this application,
they may have more recent information
than is contained in this file.
MolWeight is © Chris Johnson, 1992
_______________________________________
The Main MolWeight Window
This main window is where the molecular
formula is entered and where the result
of the calculation is displayed. The
molecular formula is entered using
chemical symbols and then RETURN is
pressed. The result is displayed in the
molecular weight icon to an "accuracy"
of seven significant figures, although
the actual accuracy will depend upon the
accuracy of the atomic weights of the
atoms in the particular formula.
This window has two further icons which
display milligrams and millimoles. By
default, the mass of 1 mmole of the
material is shown. However, you may
enter a value into either of these icons
by clicking SELECT while the pointer is
over the icon to place the caret, and
then entering the value from the
keyboard. When you press RETURN, the
corresponding value of millimoles or
milligrams will be calculated, using the
value of molecular weight displayed in
the molecular weight icon. This allows
you to calculate the mass corresponding
to a particular number of millimoles, or
the number of millimoles of a particular
mass of material.
It is even possible to enter a value of
molecular weight into the molecular
weight icon for use in such
calculations. When you do this, the
value of molecular weight would no
longer correspond to the formula shown.
The program will therefore display
"Unknown formula" in the formula icon.
_______________________________________
Entering Molecular Formulae
Molecular formulae are entered in as
near a natural manner as possible. The
program knows the chemical symbols for
all the elements. The case of the
letters is important, eg sodium must be
Na and mercury Hg. The formula is
entered in a single line and may contain
up to 254 characters. The text in the
icon will scroll as necessary when the
length becomes too big for the display.
As an example benzene would be entered
as C6H6. The program checks through the
formula for symbols it recognises, using
the numbers as separators of the
symbols. When only one atom of a
particular element is present then it is
essential to enter the figure one eg
methane would be entered as C1H4.
It is not necessary to enter the formula
in its simplest empirical form. For
example, it is acceptable to enter
methanol as C1H3O1H (you can drop a
trailing figure one).
A compound may contain several groups
the same, and as normal text, these
groups are often placed within
parentheses. You may enter such formula
in the same way, eg ferric sulphate
could be entered as Fe2(S1O4)3. The only
restriction in this version of the
program is that parentheses CANNOT be
nested.
_______________________________________
Exact Isotopes
By default, the program will carry out
all calculations using the average
atomic weights for the elements. In
certain cases (eg in mass spectrometry)
it is necessary to use accurate isotopic
atomic weights in the calculation.
Clicking SELECT on the "Exact isotopes"
icon in the main window will extend the
window and allow you to select certain
common isotopes (C12, O16, N14, H1, S32
and Cl35) for use in the calculations.
The calculation will use the exact
masses for whichever of these six icons
are selected. The exact mass for
deuterium can be used at ANY time by
using the symbol D rather than H. The
use of these six exact masses can be
switched on or off using the "Exact
isotopes" icon.
The program will also understand curly
brackets {}. These are used to enter any
symbol that itself contains a digit.
This is used for entering the symbol for
an exact isotope different to the
default isotopes mentioned above. For
example you might wish to use carbon 13
in a calculation. The program, as
supplied understands a number of
isotopes, including carbon 13. To use
such a symbol in eg methane, you would
enter the formula as {C13}1H4. You may
extend the isotopic coverage of the
program by entering your own symbols
(see below).
_______________________________________
Editing Atomic Data
The main menu includes a choice "Atoms".
Following the arrow to the right leads
to a submenu with choices
List
Edit
Save
Clicking on "List" will open a
scrolling window showing all the
elements known to the program, together
with the corresponding masses. Using
this you can see not only what elements
you can use but also what specific
isotopes are available. If you point at
an entry and double click with SELECT a
small dialogue box will be opened. This
box is the same as would be opened if
you followed the item "Edit" in the
Atoms submenu, except that the writable
icons are filled in with the data at
which you pointed, ready for editing.
This allows you to edit the old data or
enter a new symbol, and its
corresponding atomic mass. Clicking on
OK with either SELECT or ADJUST will add
the new data to that already loaded. If
you use ADJUST the menu/dialogue box
will remain on screen. The new data will
immediately become available to the
program. In order to include it in the
default file which is loaded at program
startup, it is necessary to save the
file using the "Save" option. You will
be warned if you attempt to quit the
program with unsaved data.
The total number of "elements" that can
be entered is 150, which allows a number
of special isotopes in addition to all
the known elements. The default atomic
data file does not have the elements in
periodic table order, but has the more
common elements near the start of the
table to speed up the searching process
during the molecular weight calculation.
__________________________________________
Entering Group Data
A further item on the main menu is
groups. Following this to the right
leads to a submenu identical to that for
atoms, and most of the previous section
applies again. The main difference is
that the dialogue box now allows you to
enter a molecular formula in an
identical way to the main window, and
the molecular weight is calculated in
the same way. This is useful if you are
calculating the molar mass of a range of
compounds that have a similar fragment
as part of their structure. The formula
is entered as described in "Entering
Molecular Formulae" above. Once a symbol
has been defined then it can be used as
a form of shorthand in any other
formula. For example, you may define the
symbol ph for phenyl, C6H5. You could
then enter chlorobenzene simply as
ph1Cl1.
The groups can be deleted and saved in
the same way as for atoms. The program
allows a total of 100 groups to be
defined.
_______________________________________