CORE CONCEPTS OF PROPERTIES OF GASES
Core
Concepts
1
1) What do you intend
the students to
learn about this
topic?
2) Why is it important
for students to
know this?
Core
Concepts
2
Core
Concepts
3
Core
Concepts
4
Core
Concepts
5
Core
Concepts
6
Core
Concepts
7
Core
Concepts
8
Core
Concepts
9
Core
Concepts
10
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.
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)?
4) What are the
difficulties/limitatio
ns associated with
teaching this topic?
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.
Approximations
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.Appro
ximations 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.Critical
pressure and
phase diagrams
can not be
mentioned.
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.
Approximations
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
explain
conservation of
mass in phase
changes
superficially.
They may not
know this
concept before
this concept.
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’co
ncept may not
be understood
by students due
to the inability
of keeping
trackof
particles. (also
in macro level).
They may not
be familiar with
the idea of
piston
mechanism,
how to fix a
variable. In that
case constant
pressure idea is
difficult to
visualize. And
doubling
temperature is
sometimes
confusing
because of
Kelvin-Celcius
scale usage.
In that case,
they may not be
familiar with
the piston
mechanism and
while waiting
for a system to
reach an
equilibrium
(also in
simulations)
they may think
of pressure to
change.
Because the
kinetic energy is
not observable
in daily life
examples,
students may
refuse to accept
this idea even
they see in
simulations.
I should be sure
that they are
aware of kinetic
theory
assumptions such
as the size of
molecules can be
ignored when
contrasted to the
large distances
between
molecules, the
interactions
between gas
molecules can be
ignored and at the
same temperature
the average
kinetic energy of
different gases
are equivalent.
They may think
that real gases are
always very
different from
ideal gases but I
should mention
that at standard
temperature and
pressure, most
real gases behave
qualitatively like
an ideal gas.
7) What kind of
methods or
strategies you may
use to teach this
topic? Explain the
reasons for using
these methods or
strategies.
Asking some
questions about
daily life examples
to think more
internalized way
the groups which
we combined
before like “how
can we hear voices
how can it be
possible.” ,”how
can they smell
something
pleasant or not so
nice then particles
are getting up your
nose. “ And enable
them to discuss
their ideas about
the concept.
We can ask some
questions to the
groups which we
combined before
like “where does
the weight of tree
come from” or
“what happens in
condensation
,where does liquid
comes from and
how can it be
weightable after
condensation.”We
may ensure group
discussion to share
their ideas with
their friends and it
makes them to
think more
different point of
views.After a
group discussion
we may ensure
another discussion
between groups to
think more deeply.
We may want the
students to draw or
tell how the space
between particles of
solid, liquid and gas
form of matter
differ from each
other. If they have
misconceptions
about the spaces
between particles
Ballons and
Buoyancy
simulations
explaining solid,
liquid and gas phase
differences may be
demonstrated. And
the idea of ‘flying’
particles may be
used to explain how
much spaces can
form between the
particles and they
are still in gaseous
phase. Some
discussion should
be conducted in
order them
convince about the
spaces that are not
air particles.
I will start with leading
them to critical thinking
by focusing on previous
core concepts 3&4 and
apply them to the
structure of ‘air’. I will
want them to say what
they know about the air
and write them on the
chalkboard. Then I will
mention again that ‘
Because most of the
volume occupied by a gas
consists of empty space
and there is nothing to
prevent two or more kinds
of gases from occupying
the same volume’. Then I
will remind Avogadro’s
Law and explain that
‘equal volumes contain
equal numbers of
molecules, so when we
say that air is 21 percent
oxygen and 78 percent
nitrogen by volume, this
is the same as saying that
these same percentages of
the molecules in air
consist of O2 and N2.
Similarly, in 1.0 mole of
air, there is 0.21 mol of
O2 and 0.78 mol of N2.
Then I will ask them to
explain how we smell
parfume odor and let
them to discuss. I will
apply an activity which is
spraying on parfume to
the classroom from the
door. I will say them to
wait for five minutes and
then walk around the
classroom. I will ask them
if they observe the
‘mixing homogenously’
phenomenon. Also I will
use the simulation that I
got from
http://phet.colorado.edu/si
mulations/sims.php?sim=
Gas_Properties to help
them visualize the
process.
Fistly we may
accomodate them
to re-think that
there are spaces
between particles
of gases.And we
can show the
Ballons and
Buoyancy
simoulation to
help them to
visualize that
gases are
compressible.
Asking questions
should be the first step
of this concept
teaching. These
questions may be
‘What happens when
we heat a gas?’, ‘What
may effect behavior of
gases?’, ‘What should
be the conditions to see
only the relationship
between volume and
temperature?’. With
such questions, group
discussions should be
promoted and their
ideas should be shared
and expressed. With
using simulation they
should control the
variables and discuss
what will happen
before playing
simulation. After
playing it, their
questions may arise and
these questions should
be answered in a way
that students’ confusion
around this concept
should disperse. What
resembles to this
conditions in daily lives
may be asked and it is
another way to make
the theory of
temperature-volume
relation permanent.
Relating with
previous core
concept, students
should be asked this
time to think of
making pressure
and temperature
constant, and
changing volume
with respect to
number of particles.
The question to
make them
critically think, may
be ‘why a balloon
expands and gets
bigger when you
blow in it?’.
According to their
response, group
discussions should
be promoted in a
way that they must
realize their way of
thinking is true or
not. Then the
simulation Balloons
and Buoyancy may
be used to make
clear their ideas.
Relating with core
concepts 7-8, this
time students should
be asked to discuss
about how
temperature effects
the speed of the
particles of gases.
They actually
familiar with the
Constant volume
issue but they may
not be aware of it. By
group discussions
their ideas should be
cleared and then by
the simulation
Balloons and
Buoyancy they can
observe the changes.
In addition their
attention should be
drawn to the pressure
at the same time,
because heating a
closed container leads
pressure increase
beside the kinetic
energy. Constant
pressure case should
be compared to
constant volume case,
differences and
reasons should be
discussed through the
lesson.
I will start with asking
them what ‘real gas’
and ’ideal gas’ concepts
mean to them. I slice
the chalkboard into two
parts and write their
answers to identify the
two terms. Then I will
remind them about the
kinetic theory
assumptions and apply
them wile defining
ideal gas behaviours. I
will explain them the
terms ‘non-interacting
point particles’ and
‘random motion’. Give
examples such as
comparing He-Kr,
CH4-C3H8, H2- N2
while explaining how
gases tend to be
ideality. I will mention
that in real life in
experiments we use real
gases but in laws and
calculations we assume
gases as ideal. I will
show them the
simulation of ‘ideal
gas’ that I got from
http://www.phy.ntnu.ed
u.tw. in order to see
ideal gases at
microscopic level. I
want them to change
the variables and see
the outcomes in their
own computers. I will
guide them about
changing variables and
discuss at each process.
8) What are the
specific ways of
ascertaining
students’
understanding or
confusion around
this topic (include
likely range of
responses).
We can use the
Ballons and
Buoyancy
simulation to
make meaningful
understanding of
the concept.Also
we can spray a
parfume to the
media and it
enables to student
to smell it. After
that we can apply
a post test to make
a decision that
students really get
rid of their
misconceptions.
We will make an
experiment in this
concept.Our
materials are a pair
of scale and a
coke.We divided
experiment into
two parts.In the
first part we want
from student to
weight the coke
and then we want
from the student to
think the weight of
coke after s/he
opens it.In the
second part,one
week later we
want from student
to weight opened
coke again.Than
s/he can see the
weight difference
which derives
from weight of
CO2 after two
weighing.
We may use a
simple experiment
which needs only
three injectors
which contain
three phases of
same matter.First
one is full of a
solid one second
one is full of
liquid one the last
one is full of gase
one. We want
from the students
to try squeeze all
the injectors when
they are closing
the hole of
injector.Then they
can see that to
squeeze first one
is the hardest one
,the second one is
more easier than
the first one ,in
the last one which
contains gase
phase is the
easiest one to
squeeze they can
get that there are
more spaces
between in gase
phases .
During lecture we
will draw them to
think deeply about
the space concept of
gases, homogenity
concept and the
mixing process by
asking them
questions such as
‘Can you explain the
arrangement of gas
molecules at
molecular level?’
‘What is there
between gas
molecules?’ ‘How
does parfume odor
spread in a room (by
concerning air
molecules)?’ They
may have general
difficulties in
understanding the
space concept and
visualizing the
molecular dimension.
After discussions,
explanations, activity
and simulation I want
them to write what
they have learned
about the issue with
their own words on a
piece of paper in
order to learn their
way of thinking. If
there are still
misconceptions or
lack of knowledge I
will inform them
again. I will give
them homework
about writing three
daily-life exa.mples
of homogenous gas
mixtures on their
notebooks
We may use a
simple experiment
which needs only
an injector.We
want from the
students to
squeeze the
injector when they
are closing the
hole of
injector.Then they
can see that it can
be squeezable.
Before the lesson a quiz
may be given asking
about comparing
temperature and
volume, or what
happens to a filled
balloon a day later on a
cold day and why?.
Looking to their
answers, if there is
problem with the idea
of constant pressure,
constant number of
particles or
temparature-volume
relations, these should
be predetermined. And
through the lesson,
students’ attention
should be drawn
according to their
responses. Group
discussions are also
conducted in a way that
their ideas are shared
and if there is a
contradict students try
to express their ideas to
convince others mostly.
Here s/he can have
problems with
explaining all the cases
according to her/his
theory and s/he may be
suspicious about own
theory if there is
another which explains
more cases logically.
The students who are
still refusing to accept
the ‘right theories’
should be determined
and with simulation
and other materials,
their attention should
be drawn to their
theories which cannot
explain in a logical
way. After the lesson a
post test may be given
to the students and a
homework may be
given to the students
who are still confused
about the concept and
their additional works
must be controlled and
feedback should be
given.
The strategy is the
same with the core
concept 7.
Additionally the
relating quiz
question may be
‘What happens
when you blow a
balloon and why
this is so?’
The strategy is the
same with the core
concepts 7 and 8.
Also, in the quiz
to relate constant
volume issue to
previous concepts,
the question may
be ‘what happens
if to blow a plastic
freezer bag for
example and what
is the the
difference to that
of balloon and
why?’, ‘What
happens to the gas
particles when you
heat a closed
container, what
you expect in
terms of kinetic
energy and
pressure of the
gas?’. And post
test should include
all of the 7., 8. and
9. concepts and
the similarities,
differences should
be asked. Some
cases should be
given where the
students are
wanted to select
the right answer
which explains the
given case in a
proper way etc.
At each stage of
giving a new
information I want
them to explore
their ideas such as
why do we need to
use ideal gas
assumption, why we
cannot use real
gases in rules and
calculations, if we
ignore interactions
or molecular sizes
how does it affect
other variables etc.
At the end of the
lecture I want them
to write categorize
again the properties
of real gases and
ideal gases. I will
ask them why we
need to use ideal
gas concepts with
their explanations. I
will use generally
the inqury-based
method verbally in
order to understand
how they think.