In thermodynamics, when mass as well as energy are not allowed to cross the boundary, such a system is known as _________.
isolated system
Understanding Thermodynamic System Boundaries
In the field of thermodynamics, a system is defined as a region in space or a quantity of matter chosen for study. Everything external to the system is considered the surroundings. The boundary separates the system from its surroundings. How mass and energy interact with this boundary is crucial for classifying the type of thermodynamic system.
Let's examine the different types of systems based on whether mass and energy are allowed to cross the boundary:
Defining Isolated Systems in Thermodynamics
An isolated system is a system where neither mass nor energy is allowed to cross the boundary. The boundary is completely impermeable to both mass and energy transfer. This means the total mass and total energy within the isolated system remain constant.
Comparing Different System Types
To better understand the isolated system, let's look at other types of thermodynamic systems:
- Closed system: A closed system is one where energy is allowed to cross the boundary, but mass is not. Think of a sealed container filled with gas that is heated or cooled; energy (heat) can enter or leave, but the amount of gas inside remains constant.
- Open system (or Control Volume): An open system allows both mass and energy to cross the boundary. Examples include a pump, a turbine, or even a human body. Mass flows into and out of the system, and energy is also exchanged with the surroundings. A control volume is essentially an open system, typically defined as a fixed region in space through which mass and energy flow.
| System Type | Mass Transfer Across Boundary | Energy Transfer Across Boundary |
|---|---|---|
| Isolated System | No | No |
| Closed System | No | Yes |
| Open System (Control Volume) | Yes | Yes |
Conclusion on the System Definition
The question asks for the type of system where "mass as well as energy are not allowed to cross the boundary". Based on the definitions, this perfectly matches the description of an isolated system. A closed system allows energy transfer, an open system allows both mass and energy transfer, and a control volume is another term for an open system. Therefore, the system where neither mass nor energy crosses the boundary is known as an isolated system.
Important Questions from Thermodynamics System and Processes
Select the right expression for Vander Waal’s equation for a real gas.
Which of the following pairs of thermodynamic properties can uniquely fix the state of a substance like water, irrespective of its thermodynamic state?
A Monoatomic ideal gas (y = 1.67 Molecular weight = 40) is compressed adiabatically from 0.1 Mpa 300K to 0.2Mpa. The universal gas constant is 8.314KJ/kgK. The work of the compression of gas in KJ/kg is. (Take (2)y-1/y = 1.32)
A reversible polytropic process can be described by
A gas goes through a process given by pv2 = c. It expands from state 1 of 350 kPa and 0.049 m3 to a final pressure of 150 kPa. Work delivered during this process in kJ is:
