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According to the first law of thermodynamics, a thermodynamic process is a modified version of the law of conservation of energy. It distinguishes between three types of energy transfer, namely heat transfer, thermodynamic work, and energy associated with matter transfer, and relates each of these types of energy transfer to an internal energy function of a body, which is referred to as internal energy.
In Thermodynamics, The Conservation Of Energy Is Stated In The First Law Of Thermodynamics
Energy can’t be created or destroyed because it can be transformed .
Input energy= output energy for the system
Input energy= output energy for the system
As a result, the amount of heat Q supplied to the system, less the amount of work W done by the system on its surroundings, results in an increase in the internal energy U of a closed system. The equivalent statement is that perpetual motion machines of the first kind are mathematically impossible to construct.
Points to Keep in Mind
Energy (E) is always constant in an isolated system because it has no other sources of energy.
It is a point function and property of the system to have internal energy. Internal energy is an extensive property (that is, it is mass-dependent), whereas specific energy is an intensive property (that is, it is independent of mass) (independent of mass).
The internal energy of an ideal gas is only a function of temperature in this case.
When applied to an isolated system (in which there is no transfer of energy or matter across the system boundary), the law of conservation of energy states that the total energy of the system remains constant; energy can be transformed from one form to another, but it cannot be created or destroyed.
Processes That Repeat
Clausius expressed the first law of thermodynamics for a closed system in two ways. The first way is as follows: One way referred to cyclic processes as well as the system’s inputs and outputs, but it did not refer to changes in the system’s internal state as a result of these processes. It was not anticipated that the process would be cyclic, as it was referred to as an incremental change in the internal state of the system in the other way. A cyclic process is one that can be repeated indefinitely many times, bringing the system back to its initial state. The net work done by the system and the net heat taken in (or ‘consumed,’ to use Clausius’ terminology) by the system are of particular interest for a single cycle of a cyclic process, respectively.
There is evidence that it is physically necessary for heat to be taken into a cyclic process in which the system performs net work on its surroundings, but it is also observed to be physically necessary for some heat to be removed from the system, which is significant. The difference is the amount of heat that has been converted into work by the cycle. Each time the system repeats the cycle, the net work done by the system, measured in mechanical units, is proportional to the total heat consumed, measured in calorimetric units.
When applied to a closed system, the first law of thermodynamics is violated.
In a closed system, the amount of work done is the product of the pressure applied and the change in volume that occurs as a result of the applied pressure:
w = − P ΔV
Where P denotes the constant external pressure acting on the system, and V denotes the change in the volume of the system (in litres). This type of work is referred to as “pressure-volume” work.
The internal energy of a system can either increase or decrease depending on the amount of work interaction that occurs across its boundaries.. If work is done on the system, the internal energy would increase, whereas if work is done by the system, the internal energy would decrease. Any heat interaction that occurs between the system and its environment results in a change in the system’s internal energy. The total change in internal energy is always zero, however, due to the fact that energy remains constant (as stated by the first law of thermodynamics). If energy is lost by the system, it will be absorbed by the surrounding environment as a result. A system’s ability to absorb energy implies that the energy was previously released by the environment:
ΔUsystem = −ΔUsurroundings
When the total internal energy of a system changes, the total internal energy of the surrounding changes, and the total internal energy of a system changes, it is said to have changed.
Conclusion
According to the first law of thermodynamics, the change in internal energy of a system equals the sum of the net heat transfer into the system and the net work done by the system (or vice versa). The first law of thermodynamics is expressed as U = Q + W in equation form. The change in internal energy U of the system is denoted by the symbol U.
