CORE CONCEPTS OF PROPERTIES OF GASES
Core
Concept 1
Core
Concept
2
Core
Concept 3
Core
Concept 4
Core
Concept 5
Core
Concept 6
Core
Concept
7
Core
Concept
8
Core
Concept
9
Core
Concept
10
1) What do you intend
the students to learn
about this topic?
Gases are
composed of
particles that
move randomly
and collide with
each other.
Gases have
weight
There are more
spaces between
particles of
gases compared
to solid and
liquid form of
matter.
Gases diffuse to
fill their
container.
Gases can mix in
any portion
homogeneously.
Gases are
compressible.
Under constant
Pressure and
Number of
particles(mole)
the Volume is
directly
proportional to
the
Temperature.
Under constant
pressure and
temperature
the volume is
directly
proportional to
no of particles.
Under constant
volume the
kinetic energy
of particles is
directly
proportional to
temperature.
An ideal gas is
a theoretical
gas and differs
from real
gases. The
laws of gases
apply to ideal
gases more
than real gases.
2) Why is it important
for students to
know this?
In order to
visualize
movement of
gas particles (in
a container) in a
proper way. To
understand
pressure and
kinetic theory of
gases. They
should not think
of gases as
composed of
static particles.
They can travel
and mix. Later
weight will be
built on the
particulate
nature of gases.
In daily lives,
they should be
aware of the
fact that gases
like all matters
are composed
of particles and
so they weigh.
Pressure is due
to the weight
of these
particles.
In order to
understand
differences
between solid,
liquid and gases
form in
microscopic
level, to figure
out why gases
mix easily, why
they are
compressible
and they have
greater kinetic
energy to go far
apart. They may
be able to
compare the
strength of
interactions
between
particles
comparing to
solid and liquid
forms of matter.
The need to
understand why
gases show the
same
characteristics
allover the
container. How
gases behave
when there is
density
difference in a
container or
when a parfüme
is sprayed from
a corner of the
room.
For example, why
air has the same
percentages
(almost) of its
components in
every field. To
make calculations
regarding gas
mixtures, they
should consider
homogeneous
mixing.
In order to
differentiate gases
from solid and liquid
form of matter.
Making connections
to everyday life such
that how so much gas
can be filled in a
small container like
bottle, how some
pistons work in
relation to pressure,
why a bottle of cola
makes some noise
when you open the
cap etc.
To understand
the idea of gas
expansion.
Making
connections to
everyday life
such that why a
ball gets smaller
in cold days and
visa versa. The
piston
mechanism
should be
understood
basically.
Students need to
understand what
the constant
pressure,
constant no of
particles and how
these variables
fixed. How
related
experiments
should be done
etc. How the
related gas law is
used and what
the results mean.
To relate number
of particles to
volume of a gas
under constant
pressure and
temperature.
How balloons get
bigger when you
blow in it.
In a closed
container the
behavior of gas
molecules should be
examined. They
need to figure out
what happens if
someone heats up a
closed container and
relate to pressure
phenomenon. In
daily life they can
find many examples
to this situation such
that every spray has
warning about being
careful about the
temperature, even if
the bottle is empty,
so they can explain
why it is dangerous.
They should not expect
real gases to obey the
gas laws. Why ideal
gases are mentioned
always in gas law
equations. Real gases
have differences
comparing to ideal gases
but ideal gases give
some well approximated
idea about gases’
behavior and in
experiments with real
gases would need
corrections. They should
understand under which
conditions a real gas
resembles most to an
ideal gas in order to
make mental
connections to each
other.
3) What else do you
know about this
topic (that you do
not intend students
to know yet)?
There are
complex
calculations to
measure the
average velocity
of particles’
collisions. Not
all particles
have the same
energy, how
they collide, and
their interaction.
Each gas
molecule has a
molecular
weight but we
do not explain
them in detail
in this topic.
Under typical
conditions,the
average
distance
between gas
particles is
about ten times
their diameter.
We do not
explain phase
transitions in
microscopic
level and how
much the
distance effects
the interaction
between
particles.
We do not
explain
diffusion rate
calculations.
In gas mixtures if
there are big
differences between
molecular weight of
the components
there may occur gas
phases such that the
gas which has
bigger molecular
weight may
accumulate in lower
parts of the
container.
We can not
mention about the
thermodynamic
properties of ideal
gases which
include the
compressibility
factor.
We do not
explain the
definition of
absolute zero
Charles
Law.We also
do not mention
the Boltzman
constant.
Approximation
s for real
gases. In
experiments it
would not be
yielded like it
is expected.
We do not need
to explain
avagadros
number in
calculations of
number of
particles.Approxi
mations for real
gases. It may
differ in reality
and in theory.
Even they are
weak, attractions
still occur among
the particles.
There may be
differences
related to piston
mechanism, such
that fixing
temperature and
pressure,
frictionless
piston are the
ones which
difficult to have.
The evarage
kinetic energy
and
momentum of
molecules
calculations
will not be
included.
We do not
explain Van
der Waals
forces and also
London forces
between
isomers.Critica
l pressure and
phase diagrams
can not be
mentioned.
4) What are the
difficulties/limitatio
ns associated with
teaching this topic?
Because the
representation
of the nature of
matter is
difficult and it
leads
visualization
problems.
Most of the
gases are
colorless so
their weights
can be ignored
because atoms
and molecules
are invisible to
eye.
The concept of
space is difficult
to explain and it
is confused with
air.
Because of the
nature of gases
most of them
are colorless so
it is difficult to
explain that
invisible gases
move and
diffuse.
If students’
conceptual
understanding of
‘space’ is not
sufficient it is
difficult to explain
the mixing process.
Because of the
nature of gases
most of them are
colorless so it is
difficult to explain
that gases are
compressible.
Approximation
s made in order
to express the
equations well
may lead some
limitations
through
experiments.
Same
difficulties
with core
concept 7 still
hold. Also
fixing some
variables may
be a problem
for the
experiments.
And it is not
possible to
have
frictionless,
weightless
piston to
conduct related
experiments.
Same
difficulties
with core
concept 7 still
hold. Also
expressing
kinetic energy
in terms of
heat, pressure
and speed may
be a source of
confusion.
Ideal gas
particles
having no
volume
because of
particle size
may not seem
relevant.So it
leads some
limitations
about this
topic.
5) What do you know
about students’
thinking which might
influence your
teaching of this idea?
They do not see
gas particles and
thinking about
something that
they cannot
observe in daily
life (or they are
not aware) may
seem irrelevant.
They may think
for some
triggering
factors refusing
their internal
energy in order
to explain
motion of
particles (giving
initial pulse,
wind etc.)
They may
think gas
particles as
weightless
because
especially air
is given as an
example of
gases and they
do not feel the
weight or mass
of the air.
If they do not
know the
arrangements of
of particles in
liquids and
solids,students
can not image.
They may think
the space as if
there is air
between
particles They
may be
confused with
the idea of
‘nothing’ and
‘air’ because we
call a bottle of
air as ‘empty’.
Students may
confuse about
the concept of
homogeneity.
When big
volumes
mentioned as
the container
student may
think the gas
particles to be
disappeared
such that when
you spray some
odor from one
corner of the
room because
the number of
particles is very
small students
at first could
smell the odor
but after a while
the odor would
not be effective
and they think
of disappearing
after some time
rather than
diffusing into
the room.
They may have
difficulty with
having the idea that
if a container is
filled with a
substance how
another substance
can be put in.
They may think
compression as
squeezing particles
such that making
molecules smaller
may be an idea of
compression. They
may confuse when
they think of
macroscopic and
microscopic scales
such that they may
consider a sponge
to be compressible.
The space concept
may still be
confusing because
when they think
the space is full of
air they can think
the air is
compressed not the
gas inside or the
space between gas
particles gets
smaller.
They may not
easily get used
to the Kelvin
scale to
express
temperature.
The relation
between
temperature
and heat
concepts, it
may be
difficult to
separate from
each other.
When it is said
to double the
temperature
they may insist
on thinking
just Celsius
scale and use
in the law
equation. Just
dealing with
equations may
not make sense
in terms of
what they
mean in real.
When they add
some gas into
the container
they may
expect the
pressure to
increase
because what
they put should
force them to
squeeze. In
real, most of
the time we
have closed
container
examples or
the ones which
in somewhere
it has limits to
expand. So the
student may
not be used to
these ideas
including
idealized cases
(piston,
interactions
etc.).
They may
think about
just the
temperature
raising not the
kinetic energy.
Speed and heat
may not seem
related at first.
In a closed
container,
relation
between
pressure, heat,
speed of
molecules and
kinetic energy
may confuse
students in a
way that they
may have
difficulties in
making double
connections
(relation
between heat
and pressure,
relation
between speed
and pressure
etc.). They
cannot observe
the kinetic
energy in daily
examples and
it may seem
abstract to
them. Heat
loses may
attract their
attention and
they cannot
hold the idea
of isolated
system.
They may have
difficulties for
visualization of
ideal gases
(having no size
particles) and
real gases
separately. It
may seem
meaningless to
study with real
gases if we do
not observe
them in real
life. They may
refuse using
real gases in
ideal gas
format while
making
calculations
with gas laws.
If they know
what they do
has mistakes in
it they may
detach from
the topic.
6) What are some of
the other factors
that you need to
consider that might
influence your
teaching of this
topic?
If students do
not know the
relationship
between
temperature and
kinetic energy it
will be difficult
to explain how
it effects the
movement of
particles and
collision of
particles.So we
should consider
whether
students have
clear knowledge
about these
concepts or not.
We should
consider the
density of
gases and
temperature of
media when
teaching the
weight of
gases.
It is difficult to
fixed the
students’
misconceptions
about the space
concept and the
arrengements of
the particles for
teachers.
They may not
know the term
‘diffusion’ and
how it occurs.
We should not
ignore that the
‘homogenity’conce
pt may not be
understood by
students due to the
inability of keeping
trackof particles.
(also in macro
level).
We will show
the simulation
“gas properties
”from the web
site
http://phet.color
ado.edu/simulati
ons/sims.php?si
m=Gas_Properti
es
We will show
the simulation
“gas properties
”from the web
site
http://phet.colo
rado.edu/simul
ations/sims.ph
p?sim=Gas_Pr
operties
We will show
the simulation
“gas properties
”from the web
site
http://phet.color
ado.edu/simulat
ions/sims.php?s
im=Gas_Proper
ties
We will show
the simulation
“gas properties
”from the web
site
http://phet.color
ado.edu/simulat
ions/sims.php?s
im=Gas_Propert
ies
We will show the
simulation “gas
properties ”from the
web site
http://phet.colorado.
edu/simulations/sim
s.php?sim=Gas_Pro
perties
7) What kind of
methods or
strategies you may
use to teach this
topic? Explain the
reasons for using
these methods or
strategies.
8) What are the
specific ways of
ascertaining
students’
understanding or
confusion around
this topic (include
likely range of
responses)
We will show the
simulation “gas
properties ”from
the web site
http://phet.colorad
o.edu/simulations/s
ims.php?sim=Gas_
Properties
We will show
the simulation
“gas properties
”from the web
site
http://phet.colo
rado.edu/simul
ations/sims.ph
p?sim=Gas_Pr
operties
We will show
the simulation
“gas properties
”from the web
site
http://phet.colo
rado.edu/simul
ations/sims.ph
p?sim=Gas_Pr
operties
We will show
the simulation
“gas properties
”from the web
site
http://phet.colo
rado.edu/simul
ations/sims.ph
p?sim=Gas_Pr
operties
We will show
the animation
“real gase
”from the web
site
http://www.yte
ach.com/page.
php/resources/
view_all?id=ga
s_Boyle_Charl
es_Brownian_
motion_Avoga
dro_ideal_non
_ideal_page_5
&from=search