
Quiz


According to the kinetic theory of gases…
What is the formula for Boyle’s Law?
 The student will be able to:
 Explore mixtures and movements of gases in order to
relate total pressure to partial pressure and explain gas
diffuses and effuses.
 An ideal gas is made up of gas particles that…
Have a high mass
b. Are in random motion
c. Have volume
d. Can be liquefied
e. Attract each other
a.
Gases
Mixtures and Movements
Gases: Mixtures and Movements
• A list of gear for an expedition
to Mount Everest includes
climbing equipment, ski
goggles, a down parka with a
hood, and most importantly
compressed-gas cylinders of
oxygen. You will find out why
a supply of oxygen is essential
at higher altitudes.
Dalton’s Law
 The contribution each gas in a mixture makes to the
total pressure is called the partial pressure exerted by
that gas.
Dalton’s Law
 In a mixture of gases, the total pressure is the sum of
the partial pressures of the gases.
Dalton’s Law
 Dalton’s law of partial pressures states that, at
constant volume and temperature, the total pressure
exerted by a mixture of gases is equal to the sum of the
partial pressures of the component gases.
Dalton’s Law
 Animation 17
 Observe the behavior of a mixture of nonreacting gases.
 Three gases are combined in container T.
Dalton’s Law
 The partial pressure of oxygen must be 10.67 kPa or
higher to support respiration in humans. The climber
below needs an oxygen mask and a cylinder of
compressed oxygen to survive.
Sample Problem
Sample Problem
Sample Problem
You Try!
Click Here for
Stimulation
Graham’s Law
 Diffusion is the tendency of. molecules to move
toward areas of lower concentration until the
concentration is uniform throughout.
 Bromine vapor
is diffusing
upward
through the air
in a graduated
cylinder.
Graham’s Law
 After several
hours, the
bromine has
diffused almost
to the top of the
cylinder.
Graham’s Law
 During effusion, a gas escapes through a tiny hole in
its container.
 Gases of lower molar mass diffuse and effuse faster
than gases of higher molar mass.
Graham’s Law
 Thomas Graham’s Contribution
 Graham’s law of effusion states that the rate
of effusion of a gas is inversely proportional to
the square root of the gas’s molar mass. This
law can also be applied to the diffusion of
gases.
Graham’s Law
 Comparing Effusion Rates
 A helium filled balloon will deflate sooner
than an air-filled balloon.
Helium atoms are
less massive than
oxygen or nitrogen
molecules. So the
molecules in air
move more slowly
than helium atoms
with the same
kinetic energy.
Graham’s Law
 Because the rate of effusion is related only to a particle’s
speed, Graham’s law can be written as follows for two
gases, A and B.
Graham’s Law
 Helium effuses (and diffuses) nearly three times faster
than nitrogen at the same temperature.
Graham’s Law
 Animation 18
 Observe the processes of gas effusion and diffusion.
Practice!
1. What is the partial pressure of oxygen in a diving tank
containing oxygen and helium if the total pressure is
800 kPa and the partial pressure of helium is 600 kPa?
a. 200 kPa
b. 0.75 kPa
c. 1.40 104 kPa
d. 1.33 kPa
Practice!
2. A mixture of three gases exerts a pressure of 448 kPa,
and the gases are present in the mole ratio 1 : 2 : 5.
What are the individual gas pressures?
a. 44 kPa, 88 kPa, and 316 kPa
b. 52 kPa, 104 kPa, and 292 kPa
c. 56 kPa, 112 kPa, and 280 kPa
d. 84 kPa, 168 kPa, and 196 kPa
Practice!
3.
Choose the correct words for the spaces. Graham's Law
says that the rate of diffusion of a gas is __________
proportional to the square root of its _________ mass.
directly, atomic
b. inversely, atomic
c. inversely, molar
d. directly, molar
a.
Small Scale-Lab
 Purpose:
 To infer diffuse of a gas by observing color changes
during chemical reactions.
 Be sure to wear :
 Safety goggles
 Lab apron
 Gloves
(20 min)
Small Scale-Lab
 Analysis questions 1-4
 (20 MIN)
 1. Did we accomplish the objective? Explain.
 2. Compare and Contrast Partial pressure to total
pressure.
 3. Compare and contrast Diffusion to Effusion.
 4. Explain the purpose or objective of the Small ScaleLab
 5. Was there anything from the lab that surprised you?
Were you already aware that gases can turn certain
chemical colors?
 Dalton’s Law and Graham’s Law worksheet
 Final Exam
 Review Packet Questions 16-18