5 Steps to a 5 AP Chemistry 2019

CHAPTER

8

KEY IDEA

Gases

IN THIS CHAPTER

Summary: Of the three states of matter—gases, liquids, and solids—gases are

probably the best understood and have the best descriptive model. While study-

ing gases in this chapter you will consider four main physical properties—volume,

pressure, temperature, and amount—and their interrelationships. These relation-

ships, commonly called gas laws, show up quite often on the AP exam, so you will

spend quite a bit of time working problems in this chapter. But before we start

looking at the gas laws, let’s look at the Kinetic Molecular Theory of Gases, the

extremely useful model that scientists use to represent the gaseous state.

Keywords and Equations

Gas constant, R = 0.0821 L atm mol-^1 K-^1

=

r

r

1

2

2

1

M

M

urms = root mean square speed

r = rate of effusion

STP = 0.000°C and 1.000 atm

PV = nRT

+











P  −=

na

V

()VnbnRT

2

2

PA = Ptotal × XA, where XA =

molesA

totalmoles

Ptotal = PA + PB + PC +...

‹^103