Secret Code: Going UP = Multiply . . . Going DOWN = Divide

Sample: How many molecules are there in 2.925 grams of sodium chloride?

Solution: (a) where do you start? (b) where are you going? (c) what steps will get you there?

2.925 gram NaCl
1

x

_1 mole NaCl_
58.5 gram NaCl

x

6.02 x 1023 molecules
1 mole

=

3.01 x 1022 molecules NaCl

This is a simple beginning. As questions get more complicated, this will be of more help.
It does NOT replace Dimensional Analysis (Factor-Label), but it helps give you a direction.

© 1977 James M. Liptrap

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