Untitled - Kelly Walsh High School

4 CHEMISTRY FOR THE UTTERLY CONFUSED
We indicate the state of matter that a particular substance is in by (s), (l), or (g).
Thus, H 2O(g) would represent gaseous water (steam), H 2O(l) would represent
liquid water, while H 2O(s) would represent solid water (ice).
1-3 Units of Measurement (SI)
The measurement system that you will most likely encounter is the SI (Metric)
system. Each quantity (such as mass and volume) has a base unit and a prefix
that modifies the base unit. The prefixes are the same for all quantities and are
based on a decimal system. Below are some basic SI units; we will introduce
others in later chapters:
Length—meter (m)
Mass—kilogram (kg)
Volume—cubic meter (m3 ) or liter (L)
Temperature—Kelvin (K)
Some of the prefixes that we will be using in the SI system are in the following
table. Your instructor may want you to be familiar with others.
Prefix Abbreviation Meaning
micro- m 0.000001 or 10 6
Milli- m 0.001 or 10 3
Centi- c 0.01 or 10 2
deci- d 0.1 or 10 1
Kilo K 1,000 or 10 3
Mega- M 1,000,000 or 10 6
Sometimes it is necessary to convert from a measurement in the English system
to a measurement in the SI system. (The English system is sometimes referred
to as the U.S. Customary system of units.) There are numerous SI/English conversions.
Consult your book and check with your instructor to see which they
recommend. We will be using the following in many of our examples:
Length: 1 inch (in) 2.54 centimeters (cm)
Mass: 1 pound (lb) 453.59 grams (g)
Volume: 1 L 1.057 quart (qt)
We will be dealing with two types of numbers in chemistry—exact and measured
ones. Exact values have no uncertainty associated with them. They are