convert to moles

Stoichiometry by the Recipe Method: SBR

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g to moles
gas vol to moles
number to moles
sol to moles

This section is presented as a brief introduction to converting different forms/quantities of matter into moles. If you know how to do this already, this section may be skipped. If not, this intro. is very brief. You should refer to your teacher and book for additional examples and practice problems.

Depending on the computer you are using, you might be able to use a calculator in the accessories area. See your teacher or computer manual for further help.

In introductory chemistry courses, students are generally asked to convert a given quantity of matter into moles and possibly back into some other form at the end of the problem. The most common forms of matter are:

	as a solid in grams,
	as a gas in liters of gas at conditions known as STP,
	a number of molecules or atoms,

Whichever method you use to solve stoichiometry problems, you will have to learn how to convert to moles. It is assumed that many of you already know how to do these conversions.

For those of you who do not, please click on the highlighted word above to go to a mini-tutorial on that topic.

I prefer to use the factor label method on mole conversions, yet, based on student input last year the above model was tested out.

You cannot go directly from any unit on the top line to another unit on that line. You have to convert into moles first.

For those of you who do NOT know how to convert between

Mass number of Volume of
\ molecules a gas at STP

\ ! /

Molar mass 6.02 E23 22.4 L MOLAR CONVERTERS

\                   !                 /
\                 !                 /
\               !                /
\              !             /
moles **

There are many ways to convert matter to moles. For purposes of this tutorial, you should check with your sources and teacher on how to determine molar mass of a compound, and how to convert volume of a gas at STP to moles.

Teacher's tip:
The relative position of the parts of this picture are useful. Since mass is above mole, to get to mole you would have to go down. The mathematical operation to do this is to divide by the appropriate molar mass. In fact, whenever going down in this graphical organizer, you will end up dividing by the molar converter. Conversely, when going up, multiply.

This is easily remembered by the DDUM saying (pronounced DaDum):

Down Divide, Up Multiply

Author's note: This simplistic rule works for the above conversions. There are other ways chemicals can be distributed to you, notably solutions. Here the material may be provided to you in various ways: molarity, molality, percent, proof, ppm, and even by density measurements. For these, the interested student should seek guidance from their instructor.

For instruction in molarity to moles see molar solution - usually expressed as moles per Liter symbolized by M.

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This page was last updated: 03/02/04 04:40 PM