Hi. It's Mr. Andersen and this is chemistry essentials video 48. It's on energy transfer
or how energy gets from one place to another. And a great example of that is in a four stroke
engine. So in an internal combustion engine. So if we started playing, what really is going
on is that we're taking in gasoline and air into a combustion chamber. There's an explosion
which drives the piston down, turns a crack shaft. We're also getting rid of that exhaust.
And what it's really doing is transferring the energy in that gasoline into mechanical
energy of the movement of your car. Now we lose a lot of that energy to heat. But what
we're really doing is moving energy from one place to another. And so imagine we have two
systems. And that system one has more energy than system two. If they're ever connected
we can transfer energy from one to another. Now the one we talked about in the last video
was thermal energy or energy transferred through what's called heat. But we can also do work
which is really applying a force over a certain amount of distance. And so that could mechanical
in nature, electrical, light or it could even be chemical in nature. And so what we're really
talking about is how we can move energy from one place to another and transfer that energy.
Now in this chemistry class you're really only going to do calculations related to volume
change. And that's why I started with that internal combustion engine. As we change the
volume inside that combustion chamber we can do work based on that. To show that energy
transfer I want to start with a PHET simulation. And so in this simulation on the left side
is going to be the source of that energy. Then we're going to convert the energy in
the middle. And then you could think of this as system two over on the other side. And
so for the first parts of this simulation we're just going to be heating up water. You'll
see increases in temperature. But what you're really going to be able to see is how energy
is being transferred from one form to another. And so we're going to have five different
forms of energy, from mechanical all the way down to chemical. And remember that heat or
that transfer energy through heat is going to be thermal energy. And so let me start
it playing. So what we're doing is releasing mechanical energy from the water which is
turning a turbine and converting that mechanical energy into electrical energy. It's running
a heater which is heating up that water. Now let's say we change that source of energy
to solar energy. Well it doesn't do anything until I add a solar panel. And now it's going
to convert that light energy into electrical energy. And that electrical energy again is
going to heat up the water. And you can see that the amount of energy that we have is
being conserved. Now let me add a little bit of steam. So we're getting the mechanical
energy of the flow of the water molecules. A lot of thermal energy. And now that's turning
a turbine again which is creating electrical energy. And that electrical energy again is
heating up that water. We're getting higher kinetic energy in the water and we're transferring
the energy as heat. Now let's put this girl on a bike and what she's doing is converting
chemical energy inside her body into mechanical energy. We're giving off some of that energy
as heat, but that again is turning a turbine again. Oops. We've got to feed her and give
her a little more chemical energy. And we can make that water boil or we could transfer
it into a light bulb where we're heating up that filament. You could see thermal energy.
And then we're giving light energy back again. As long as we keep feeding her everything
is going to be good. And so through this simulation you can see that we're transferring energy.
We're transferring that energy either as work or a force applied over a distance. Or we're
releasing some of that energy as thermal energy or heat. And so in thermodynamics, which is
really what this unit is about, what we're dealing with is transformations, transformations
that involve work, heat and the transfer of energy. And that's really what thermodynamics
is. And so if we were to look at that piston again in that internal combustion engine,
what's going on? Well we're changing that chemical energy that's found in the gas and
the compressed air inside that combustion chamber, and we're transferring that into
mechanical energy or work. And so what really happens in that piston is we have an explosion.
And what that does is convert that chemical energy into the energy of the expansion of
those molecules. And so it's really doing is work on that piston. It's driving that
piston down and then this occurs over and over and over again. And so did you learn
to relate the magnitude, how big it is, the type and the direction of energy transfer?
Now what do we mean by type. Remember that type could energy transfer through heat. Or
it could be energy transfer through work. And also did you learn that the energy is
going to be conserved? Well I hope so. And I hope that was helpful.