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Everyone is hot. Or rather, everyone has heat. Every atom and molecule in your body undergoes constant random motions that are impossible to predict. Those random motions are what we call heat energy. Thermodynamics is the study of the movement of heat. If you touch a block of ice, it isn't always pleasant unless it's a really hot day. If you touch a hot pan out of the oven you'll burn yourself.
Both of those things happen because of how fast heat is moving. The heat from the hot pan moves into your hand rapidly, and when touching an ice cube, you lose your own body heat fast. Heat transfers from hot places to cold places - or in other words, heat spreads out.
Extreme heat or cold can damage our tissues, so it's a pretty important thing to understand. It's also how we've been able to build refrigerators and large insulated coolers to take to the beach.
These are examples of the many things we can do with heat if we understand how it moves within or between systems. A system is just a particular object or area we're looking at. Our system could be the inside of a thermos flask, or it could be the whole human body or just our skin, or the gas inside a piston.
We choose the system we want to look at for convenience. Then we can look at how heat moves in, out and within that system. We can look at how the system changes. A thermodynamic process is any process that involves heat energy moving within a system or between systems. In this lesson, we're going to look at the four types of thermodynamic processes. The four types of thermodynamic process are isobaric, isochoric, isothermal and adiabatic. Those terms are pretty hard to understand just from the names, so let's break them down one at a time.
An isobaric process is one where the pressure of the system often a gas stays constant. Pressure is related to the amount of force that the molecules apply to the walls of the container.
Imagine that you have a gas inside a movable piston and you heat that gas up. By heating the gas up you make the molecules move faster, which would normally increase the pressure. But at the same time the piston expands, increasing the volume and giving the molecules more room to move. Since the walls of the container are now bigger, the pressure can stay the same even though the molecules are moving faster.
That makes it an isobaric process. An isochoric process is one where the volume of the system stays constant. Again, 'iso' means the same and 'choric' means volume. Volume is the amount of space the material takes up. So this would be like heating a gas in a solid, non-expandable container.
The molecules would move faster and the pressure would increase, but the size of the container stays the same. An isothermal process is one where the temperature of the system stays constant.
Thermal relates to heat, which is in turn related to temperature. Temperature is the average heat movement energy of the molecules in a substance. An example of an isothermal process would be if we took a gas held behind a movable piston and compressed that piston: the volume has decreased, and the pressure behind the piston has increased, since the molecules have less space in which to move.
When you compress a piston, you're using energy - you're doing work on the gas - so normally the molecules would gain energy and move faster, and the temperature would increase. So the only way for an isothermal process to happen is if all that energy you put into compressing the gas comes out again, for example by putting a cold reservoir in contact with the piston.
In an isothermal process, whatever energy we put into the system immediately leaves the system again. In the real world, you would have to move the piston infinitely slowly to make this happen, but you can still do something that gets close to this by moving super slowly. An adiabatic process is one where no heat flows in or out of the system. We can't heat up the system by putting a hot reservoir next to it, and we can't cool down the system by putting a cold reservoir next to it.
The system is perfectly insulated. In an adiabatic process, you take the gas behind the piston and move it up or down to change the volume, and both the pressure and the temperature change as a result. If you compress the piston, both the temperature and pressure increase because you've added energy to the system by doing work pushing the piston down. If you let the piston expand, both the temperature and pressure decrease. For this to happen in real life, you would either need a perfect insulating material or you would need to push the piston infinitely fast.
Thermodynamics is the study of the movement of heat, which is the motion of molecules. A thermodynamic process is when heat moves, either within systems or between systems. There are four types of idealized thermodynamic processes: an isobaric process is one where the pressure stays constant, and the temperature and volume change relative to each other.
An isochoric process is one where the volume stays constant, and the temperature and pressure change relative to each other. An isothermal process is one where the temperature stays constant, and the pressure and volume change relative to each other. An adiabatic process is one where no heat flows in or out of the system: pressure, volume and temperature all change relative to each other. Together, these four processes help us understand how heat moves.
Although many of them are not possible in real life, by understanding these idealized situations we can better understand the more messy and complex situations in the world around us. Thermodynamic process - any process that involves heat energy moving within a system or between systems. To unlock this lesson you must be a Study. Create your account. The following situations might be described or well approximated as one of the 4 types of thermodynamic systems.
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Second Law of Thermodynamics: Entropy and Systems. What is Specific Volume?
Thermodynamic processes : isothermal, adiabatic, isochoric, isobaric
In fact, isothermal means the temperature remains constant, and adiabatic means that there are no heat transfer processes. All four processes can be presented on a p-V graph the blue lines are isotherms — lines showing the points at the same temperature :. From the first law of thermodynamics :. Substitute in the definitions of heat capacity and work:. These equations are used a lot in Carnot cycles and Otto cycles. Back to Contents: Physics: Thermodynamics. You are commenting using your WordPress.
Physical Chemistry : Isothermic, Isobaric, and Adiabatic Processes
Figure 1. Beginning with the Industrial Revolution, humans have harnessed power through the use of the first law of thermodynamics, before we even understood it completely. This photo, of a steam engine at the Turbinia Works, dates from , a mere 61 years after the first explicit statement of the first law of thermodynamics by Rudolph Clausius. Figure 2. Schematic representation of a heat engine, governed, of course, by the first law of thermodynamics.
Thermodynamic Processes: Isobaric, Isochoric, Isothermal & Adiabatic
For an isothermal process there is no change in temperature, therefore, the temperature is a constant. Hence the name isothermal iso means the same and thermal means temperature. A simple explanation of this is that all the heat applied to the system is used to do the work. A piston is a good example for this phenomenon. Calculate the change in internal energy for this gas.