SparkNotes: SAT Chemistry: Basic Measurement and Calculation Review
Shopping Cart
0 items0 items
Checkout
Search SparkNotes!
Help
|
Log in
|
Sign Up for a Free AccountHelp Log in Sign
Up for a Free Account
Message Boards
SAT Chemistry Test Prep
Test Prep Centers
SAT Chemistry Test Center
Basic Measurement and Calculation Review
SparkCollege
Find a School
<< return to the previous section | continue to the next section >>
College Admissions
12.1 The SI System
Financial Aid
College Life
Basic Measurement and Calculation Review
The SAT II Chemistry test will not directly test you on any of the skills that this appendix discusses.
However, a good working knowledge of the information in this chapter will still prove very helpful
during the exam. Remember, you can’t use a calculator during the test!
Your Account
See all available SparkNotes test
prep.
<< return to the previous section | continue to the next section >>
Help | Feedback | Make a request | Report an error | Send to a friend
SAT Vocabulary Novels
are fast-paced, fun and
feature 1,000 of the
most frequently tested
SAT vocabulary words.
More...
The AP Powerpack is the
smarter, better, faster
way of mastering the AP
exam—and in just five
days!
More...
Basic Measurement and Calculation Review
Contact Us | Privacy Policy | Terms and Conditions | About
SAT II is a registered trademark of the College Entrance Examination Board
which was not involved in the production of, and does not endorse, this product.
©2006 SparkNotes LLC, All Rights Reserved.
file:///C|/Documents and Settings/lzh/
面/chemistry/chapter12/chapter12.rhtml.htm [2007-2-28 22:07:37]
SparkNotes: SAT Chemistry: The SI System
Shopping Cart
0 items0 items
Checkout
Search SparkNotes!
Help
|
Log in
|
Sign Up for a Free AccountHelp Log in Sign
Up for a Free Account
Message Boards
SAT Chemistry Test Prep
Test Prep Centers
SAT Chemistry Test Center
Basic Measurement and Calculation Review
SparkCollege
Find a School
<< return to the previous section | continue to the next section >>
College Admissions
12.1 The SI System
Financial Aid
College Life
The SI System
The Système Internationale (International System), SI, more commonly known as the metric system,
is the only system of measurement that you’ll see on the SAT II Chemistry test. Here’s a quick
refresher course on how to use this system.
Standard Prefixes
The metric system is fairly straightforward. The table of prefixes below is only partial, but it includes
the ones that you need to be familiar with for the test.
Prefix
Power
Meaning
Examples of measurements
nano (n)
10-9
one-billionth
nanometer (nm): wavelength of light
micro (m)
10-6
one-millionth
micrometer (mm): width of a hair
milli (m)
10-3
one-thousandth
milliliter (mL): volume of acid in burette
centi (c)
10-2
one-hundredth
centimeter (cm): length of paper
deci (d)
10-1
one-tenth
deciliter (dL): amount of liquid
kilo (k)
103
one thousand times
kilogram (kg): your weight
Also useful to know are the units in the table below. Most of them will probably be familiar to you.
What is being measured
Common units
length
meter (m)
mass
gram (g)
volume
liter (L) or cm3
temperature
degree Celsius (˚C) and kelvin (K)
time
second (s)
pressure
kilopascal (kPa); atmosphere (atm); mmHg
energy
joules (•J); calorie (cal)
amount of substance
mole (mol)
Scientific Notation
This is an easy way to express really large or really small numbers conveniently. The general format for
numbers expressed this way is
some number
file:///C|/Documents and Settings/lzh/
10some power
面/chemistry/chapter12/chapter12section1.rhtml.htm (1 of 4) [2007-2-28 22:07:40]
Your Account
See all available SparkNotes test
prep.
SparkNotes: SAT Chemistry: The SI System
For instance, 6.022
1023 is really big, and 3.00
10-6 is really small. Notice that the proper
position for the decimal is to the right of the first nonzero digit. If you must move the decimal to get it
into this position, moving the decimal to the left makes the exponent appear larger, while moving
decimal to the right makes the exponent appear smaller. For example, 0.000567 in scientific notation
would be 5.67
10–4.
You need to be able to handle numbers of this sort without a calculator. Basically, you need to
remember the following. For multiplication, add exponents, and for division, subtract exponents. To
get the log of a value, raise it to the power of ten. This is mostly useful for pH calculations. Now try
some problems.
Example
(4.5
105)(3.0
108).
Explanation
The answer is 1.35
1014 (or rounded, 1.4
1014). In solving this, think: 3
5 = 15, and then add
the exponents: 5 + 8 = 13. Move the decimal to the right of the first nonzero digit, or one place to the
left.
Example
Try another one:
.
Explanation
The answer is 3.4
(10) = -12.
10-12. In solving this, think: 6.8/2 = 3.4, and then subtract the exponents: (-2) -
Example
Let’s try another: Find the log of 1.0
10-7.
Explanation
The answer is -7. The thought process is as follows. The log of 1.00 is 0. The log of 10-7 is just the
power of 10.
Temperature Conversions
The only two temperature scales that are needed for the SAT II Chemistry test are the Celsius scale
and the Kelvin scale. One degree on the Celsius scale is the same increment as 1 kelvin on the Kelvin
scale.
Celsius scale: This is the scale used in the chemistry laboratory for most experiments. The freezing
point of water is 0ºC, and the boiling point of water is 100ºC. This was the original metric standard for
temperature.
Kelvin scale: This is the scale used for working through gas law problems. There are no negative
numbers on this scale. At 0K, all motion theoretically ceases.
Calculations Involving Metric Measurements (Dimensional
Analysis)
Dimensional analysis offers an easy way to solve problems using conversion factors and unit
cancellations. Conversion factors are ratios that equal 1. You know many of these ratios of
equivalencies from everyday living. For example, 1 gallon equals 4 quarts, 12 inches equals 1 foot, etc.
This is a useful technique for calculations that might come up on the test, so work through the
following problems to practice it.
Example
file:///C|/Documents and Settings/lzh/
面/chemistry/chapter12/chapter12section1.rhtml.htm (2 of 4) [2007-2-28 22:07:40]
SparkNotes: SAT Chemistry: The SI System
How many inches tall is a person who is 5 feet, 4 inches tall?
Explanation
Example
How many milliliters would there be in 3.5 liters of soda?
Explanation
You’ll have to do plenty of conversions like the one above to solve problems on the exam. Be sure that
you are familiar with all the metric prefixes listed earlier so that you can be successful when you need
to convert numbers.
Density
Density is a complex unit. It is defined as mass per unit of volume:
All pure substances have a unique density at a given temperature. Density is an intensive physical
property, meaning that it does not change with sample size. Usually the solid form of a pure substance
is denser than the liquid form of the same substance. This makes sense because in most solids, the
particles are much closer together than in their liquid counterparts.
Typical units for density of solids and liquids are grams per milliliter or grams per cubic centimeter.
(Remember: 1 cm3 = 1 mL.) Typical units for density of gases are grams per liter.
Example
Find the density of a substance that has a mass of 45.0 g and a volume of 3.0 mL.
Explanation
Example
What would be the mass of a substance that occupies a space of 2.0 cm3 and has a density of 7.5 g/
cm3?
Explanation
. Rearrange the equation to solve for mass: M = D
V.
Then
M = (7.5 g/cm3)(2.0 cm3) = 15 g
<< return to the previous section | continue to the next section >>
file:///C|/Documents and Settings/lzh/
面/chemistry/chapter12/chapter12section1.rhtml.htm (3 of 4) [2007-2-28 22:07:40]
SparkNotes: SAT Chemistry: The SI System
Help | Feedback | Make a request | Report an error | Send to a friend
Beat the SAT II Math IC
test with the latest book
from the experts at
SparkNotes.
More...
SAT Vocabulary Novels
are fast-paced, fun and
feature 1,000 of the
most frequently tested
SAT vocabulary words.
More...
Basic Measurement and Calculation Review
Contact Us | Privacy Policy | Terms and Conditions | About
SAT II is a registered trademark of the College Entrance Examination Board
which was not involved in the production of, and does not endorse, this product.
©2006 SparkNotes LLC, All Rights Reserved.
file:///C|/Documents and Settings/lzh/
面/chemistry/chapter12/chapter12section1.rhtml.htm (4 of 4) [2007-2-28 22:07:40]