Page 303 - Theory and Problems of BEGINNING CHEMISTRY

APPENDIX

Scientific

Calculations

This appendix introduces two mathematics topics important for chemistry students: scientific algebra and
electronic calculator mathematics. The scientific algebra section (Sec. A.1) presents the relationships between
scientific algebra and ordinary algebra. The two topics are much more similar than different; however, since
you already know ordinary algebra, the differences are emphasized here. The calculator math section (Sec. A.2)
discusses points with which students most often have trouble. This section is not intended to replace the instruc-
tion booklet that comes with a calculator, but to emphasize the points in that booklet that are most important to
science students.
For more practice with the concepts in this appendix, you might recalculate the answers to some of the
examples the text.

A.1. SCIENTIFIC ALGEBRA

Designation of Variables
To solve an algebraic equation such as
5x + 25 = 165

we first isolate the term containing the unknown (5x) by addition or subtraction on each side of the equation of
any terms not containing the unknown. In this case, we subtract 25 from each side:
5x + 25 − 25 = 165 − 25
5x = 140

We then isolate the variable by multiplication or division. In this case, we divide by 5:
5x 140
=
5 5
x = 28
If values are given for some variables, for example, for the equation
y
x =
z
292

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