Dimensional analysis allows us to change the units used to express a value. For instance, it allows us to convert between volume expressed in liters and volume expressed in gallons. The following video gives a brief overview of dimensional analysis, including conversion between the amount of a substance expressed in "number of molecules" and the amount of a substance expressed in "moles of molecules."

Text version of this movie.

Remember that it is always a good idea to write both the unit and substance associated with any chemical quantity; e.g., 1.3 g H2O or 5.4 x 1023 molecules H2 instead of 1.3 g or 5.4 x 1023 molecules. This will help you keep track of your quantities correctly and prevent you from making mistakes in your computations.

Conversion table for problems below.

Mass:

1 lb = 16 oz = 453.6 g

1 kg = 1000 g = 2.20462 lb

Volume:

1 gal = 3.7854 L

1 cm³ = 1mL

These tutorials are part of a complete stoichiometry course developed with the Open Learning Initiative at Carnegie Mellon University. To access the entire course, please see http://www.cmu.edu/oli/courses/enter_chemistry.html.

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