The Kinetic Molecular Theory of Gas (part 1)
Summary
TLDRThis lesson introduces the concepts of kinetic energy, phase changes, and the states of matter, emphasizing how gases differ from solids and liquids. It explains the kinetic molecular theory of gases, which outlines five key rules: gas particles are small and widely spaced, they move randomly in constant motion, collisions are elastic, there are no forces of attraction or repulsion between particles, and the average kinetic energy depends on temperature. The lesson highlights how these principles help us understand gas behavior, setting the foundation for future problem-solving.
Takeaways
- 🧪 The lesson begins with a review of kinetic energy, phase changes, and states of matter, which serve as foundational knowledge for understanding gases.
- 💨 Kinetic energy is energy possessed by an object due to its motion, with faster objects having more kinetic energy.
- 🔴 In solids, particles are tightly packed with minimal kinetic energy, while in liquids, particles have more freedom to move and more kinetic energy.
- 🏃 Gases have the most kinetic energy, with particles moving rapidly and not connected to their neighbors.
- 📏 The Kinetic Molecular Theory of Gases provides rules for understanding how gases behave, even though no real gas follows all the rules perfectly.
- 🔬 Rule 1: Gas particles are extremely small and far apart, leaving lots of empty space between them.
- 🔄 Rule 2: Gas particles are in constant random motion, colliding with each other and the walls of their container.
- ⚡ Rule 3: Collisions between gas particles and the container walls are elastic, meaning no kinetic energy is lost.
- 🔗 Rule 4: There are no forces of attraction or repulsion between gas particles, unlike some other types of particles.
- 🔥 Rule 5: The average kinetic energy of gas particles depends on the temperature – higher temperatures result in faster movement.
Q & A
What is kinetic energy?
-Kinetic energy is a type of energy that an object possesses if it is in motion. The faster something moves, the more kinetic energy it has.
How does the kinetic energy of gas particles compare to that of solids and liquids?
-Gas particles have the most kinetic energy because they move rapidly and freely, while particles in solids have the least kinetic energy as they are packed tightly and move very little. Liquids have intermediate kinetic energy.
What are the key differences between solids, liquids, and gases in terms of particle movement?
-In solids, particles are tightly packed and have very little movement. In liquids, particles have more kinetic energy and can move around but remain close to each other. In gases, particles have the most kinetic energy, moving freely and colliding with each other and the container walls.
What is the Kinetic Molecular Theory of gases?
-The Kinetic Molecular Theory of gases is a set of assumptions that describe how gas particles behave. It includes concepts like constant random motion, elastic collisions, and no forces of attraction or repulsion between particles.
What is meant by 'elastic collisions' in the context of gas particles?
-Elastic collisions refer to interactions between gas particles or between gas particles and the container walls, where no kinetic energy is lost during the collision. The particles bounce off each other or the walls without losing speed.
How does temperature affect the movement of gas particles?
-The average kinetic energy of gas particles depends on the temperature of the gas. As the temperature increases, gas particles move faster, resulting in more collisions and higher kinetic energy.
Why is it difficult to depict gas particles visually in diagrams?
-Gas particles are extremely small and spread far apart relative to their size, making it hard to represent them accurately in visual diagrams. For instance, if gas particles were the size of marbles, their container would be as large as a football stadium.
What does the term 'ideal gas' refer to?
-An ideal gas is a theoretical gas that follows all the rules of the Kinetic Molecular Theory perfectly. However, in reality, no gas behaves perfectly, but most gases only deviate slightly from these rules.
Do gas particles experience forces of attraction or repulsion?
-No, according to the Kinetic Molecular Theory, gas particles do not experience forces of attraction or repulsion. They neither attract each other nor repel each other when passing by.
What happens when gas particles collide with each other or with the container walls?
-When gas particles collide with each other or the container walls, they undergo elastic collisions, meaning they bounce off without losing kinetic energy.
Outlines
🌬️ Introduction to Gases and Kinetic Energy
The first lesson in the unit introduces gases, starting with a review of kinetic energy, phase changes, and the states of matter. Kinetic energy is defined as the energy of motion, with faster movement equating to more kinetic energy. This concept is applied to the states of matter: solids have particles tightly packed with minimal kinetic energy, liquids have particles with more freedom and movement, and gases have particles with the most kinetic energy, constantly moving at high speeds. The lesson sets the stage for understanding gases through the 'Kinetic Molecular Theory of Gases,' which provides rules for conceptualizing gas behavior.
📏 The Kinetic Molecular Theory of Gases: Rules and Assumptions
This section outlines the key rules of the Kinetic Molecular Theory of Gases. Gas particles are extremely small and far apart, with significant space between them compared to their size. They are in constant, random motion, colliding elastically with each other and container walls, meaning their kinetic energy is preserved during collisions. Furthermore, there are no forces of attraction or repulsion between gas particles, and their behavior is influenced by temperature, with higher temperatures increasing their speed. These assumptions help simplify the study of gases, though real gases may deviate from these idealized rules under certain conditions.
Mindmap
Keywords
💡Kinetic Energy
💡Phase Changes
💡States of Matter
💡Kinetic Molecular Theory
💡Ideal Gas
💡Elastic Collisions
💡Random Motion
💡Temperature
💡Attraction and Repulsion Forces
💡Particle Size and Spacing
Highlights
Introduction to gases and kinetic energy review, emphasizing phase changes and states of matter.
Definition of kinetic energy as the energy possessed by any moving object, with examples like a truck and an atom.
Kinetic energy increases with speed; a faster object has more kinetic energy than a slower one.
Overview of the states of matter: solids, liquids, and gases, with a focus on particle arrangement and energy levels.
In solids, particles are packed tightly, with low kinetic energy and limited movement.
In liquids, particles have more kinetic energy and can move freely but still remain close to their neighbors.
In gases, particles have the highest kinetic energy, move rapidly, and are not connected to their neighbors.
Introduction to the kinetic molecular theory of gases, a set of rules for conceptualizing gas behavior.
Definition of an ideal gas, which perfectly follows all the rules of the kinetic molecular theory.
Real gases rarely follow all the rules, but we assume ideal gas behavior for most problems.
First rule of the kinetic molecular theory: Gas particles are very small and far apart relative to their size.
Second rule: Gas particles are in constant random motion and frequently collide with each other and container walls.
Gas particle collisions are elastic, meaning kinetic energy is conserved in the collisions.
There are no forces of attraction or repulsion between gas particles, unlike particles in liquids.
The average kinetic energy of gas particles depends on the temperature—the hotter the gas, the faster the particles move.
Transcripts
this is the first lesson in our unit
about gases we're going to start off
this unit with a quick review about
kinetic energy phase changes and states
of matter um that's information may be
familiar to you but uh even if it is I
think it'll still be a useful review
then we're going to talk about a theory
with a really scary name the kinetic
molecular theory of gases which is a lot
scarier than it sounds and it gives us
some rules for how we can think about
gases and finally we'll look at a few
unique properties of gases uh that are
very different from those of solids or
liquids so let's take a look at uh
kinetic energy first of all kinetic
energy is a type of energy that anything
has if it's moving so a Mac Truck if
it's barreling down the highway it has
kinetic energy and even a tiny little
atom moving around has kinetic energy
thing about kinetic energy is the faster
something's moving the more kinetic
energy it has so kid sprinting down the
street has more kinetic energy than that
same kid just walking down the street
likewise an atom that's moving really
fast has more kinetic energy than that
same atom that's moving very
slowly the idea of kinetic energy is
particularly important when we start
talking about phases of matter let's
take a quick review um brushing up on
what we probably already know about
phases of matter I have here indicated
um some certain representations of
phases of matter I have a container and
some particles in it I've I've got a
representation of a solid a liquid and a
gas let's start with a solid a solid
here like all the other phases of matter
is made up of particles that's what
these little red circles represent
particles can be either atoms or they
can be molecules that are formed by the
atoms coming together either way all
things are all matter and all things are
made up of particles so in a solid the
particles as you can see are packed
together really tightly they have very
little kinetic energy they're moving
around a little bit but for the most
part they're locked in place and they're
locked to their
neighbors the particles in liquid have
more kinetic energy they're moving
around and they're Freer to move they're
still locked in with their neighbors to
some degree but they're swimming around
they're swimming in close proximity to
the particles
nearby gases on the other hand have a
ton of kinetic energy in fact to make
this picture even more accurate what I'm
going to do is I'm going to add a few
arrows these arrows are going to
represent the fact that these gas
particles are in constant motion they're
moving mov around all over the place
they're banging against each other and
they're banging against the sides of the
container that they're in in fact these
gas particles are moving so quickly that
a room temperature they have about an
average speed of a th000 miles an hour
that's just how fast they're zipping
around here in this
container so solid liquid and gas have
increasing amounts of kinetic energy
gases have the most kinetic energy
they're flying around in there and
they're not connected at all to their
neighbors now this is a very superficial
representation of what a gas looks like
but often we're going to want to look at
problems and think about gas
conceptually in a way that'll make it
necessary um to have some some deeper
understanding about what a gas is and
how these gas particles behave we
obviously can't see gas so in the
problems that we're going to do later on
we have to have a way to think about it
a way to conceptualize it so it's useful
to set up a series of rules for how we
expect gases to behave we'll make these
rules or assumptions and then we can
keep them in mind when we have to solve
problems or do
calculations now this list of rules is
What's called the kinetic molecular
theory of gases often times it's just
referred to as the kinetic theory of
gases and as I said it's a list of rules
expectations assumptions of how we
expect gases to behave now if a gas
follows every single one of these rules
we call it an ideal gas but in the real
world world it's very hard to come up
with an example of anything that always
follows all the rules we might want to
think that there exists something like a
perfect student an ideal student or an
ideal kid but rarely that's the case
almost always we find a few exceptions
to the rules and so because of that it's
helpful to think of an ideal gas but in
the real world none of these gases that
we're going to talk about ever follow
all the rules all the time at the end of
this unit we'll look look at some
particularly bad offenders gases which
break rules more more often than others
do and we'll look at certain situations
that cause gases to break the rules for
the most part though in all the gases
that we're going to look at now we're
going to assume that they're ideal gases
we're going to assume that they follow
all the rules all the time and for the
most part most of these gases only break
the rules in Little Bits once in a while
so we we can safely assume that all the
gases we're deal dealing with these
rules R of the kinetic molecular theory
so let's take a look at what some of the
rules of this are and once again
sometimes it's just referred to as a
kinetic theory going to write down here
kinetic
molecular
theory of
gases so in no particular order let's
take a look at uh some of the
assumptions that we make about gases
here's the first
one gas consist of very small particles
that are far apart relative to their
size this is something that's very
difficult to depict visually and I
certainly didn't do a good job of it in
the phase in the phase diagrams that I
just showed
you gas particles in the uh in the
picture that I drew you look like
they're the size of marbles in a glass
jar this isn't true at all gas particles
are so tiny that instead of think of
them as marbles in a glass jar if the
gas particles are the size of marbles
are contain container would be like the
size of a football stadium so these guys
are absolutely tiny and there's a ton of
empty space between them that's the
first thing that we want to keep in mind
when we're dealing with
gases here is a uh a second thing and
this is very important gas particles are
in constant random motion we hinted
about this earlier with those arrows
that I drew of the the gas is moving
around the moving particles constantly
collide with each other and with the
walls of the container so so all the
time whenever I have gas in any sort of
a container or even if it's just in a
room these guys are zipping around
they're bouncing against the walls and
they're bouncing against each
other now let's think about those
balances a little bit more there are a
variety of ways for things to to bounce
into each other and here we say that
collisions between gas particles and
container walls are elastic
collisions what's an elastic Collision
let's think about two balls of slime
these two balls of slime on either Sid
come together and what's going to happen
they're just going to hit each other and
they're
gr this is what we call an inelastic
collision that means that the kinetic
energy that both of these guys had got
wasted in the Collision these guys were
both moving they came together and they
just kind of went blah and all the
kinetic energy to speed the motion that
they had disappears in the Collision
this is like what happens if you Chuck
an egg against the side of a wall it
hits the wall and then it just drips
down but the motion that it had the
kinetic energy
disappears that's an inelastic collision
the collision between gas particles and
container walls on the other hand are
elastic
collisions a good way to think about an
elastic Collision is think about what
happens when two red or or pink round
rubber balls hit each other they hit and
they bounce right off or one of those
pink rubber balls hits the side of a
wall bam it bounces right back the
kinetic energy isn't wasted in the
Collision this ball hits here and it has
a same amount of kinetic energy
afterwards that it had when it started
that's the exact kind of collision that
gas particles get into they Bang into
each other and they just fly right apart
or they hit the side of a container wall
and they just bounce right off it so
whenever you think about gas particles
colliding you always want to keep in the
in in mind the idea of elastic
collisions additionally we can say that
there are no forces of attraction or
repulsion between gas particles some
particles like water molecules kind of
like each other and so almost like weak
little magnets they tend to attract
other particles two particles that have
the same charge don't like each other
they're sort of afraid of each other and
so they're going to repel they don't
want to get anywhere near each other
what this law is is saying when we say
there are no forces of attraction or
repulsion between gas particles what we
mean is that gases are flying around and
they're not going to start clumping
together because they're attracted to
each other that doesn't happen there's
not that attract ction likewise let's
assume that two gas particles are
passing each other they're just going to
fly right by if they repelled each other
Zoom they'd hit out that way when they
get close that doesn't happen they don't
repel each other and they don't attract
each other
either lastly here's what I think is
probably the most important thing to
keep in mind when we're talking about
the kinetic theory of gases and that's
that the average kinetic energy of gas
particles depends on the temperature of
the gas the hotter it is the faster they
move so remember that hotter for gas
movement equals faster this is
tremendously important the hotter it is
the faster these gas particles move
around so in this kinetic theory of
gases we've looked at a few of the rules
that we always want to keep in mind
whenever we're dealing with gases and
again we're going to assume that all the
gases we're dealing with follow uh
follow these five rules that we just
talked about
関連動画をさらに表示
5.0 / 5 (0 votes)