Properties of Systems MCQ Quiz in தமிழ் - Objective Question with Answer for Properties of Systems - இலவச PDF ஐப் பதிவிறக்கவும்

Concept:

Properties

All measurable characteristics of a system are known as properties.

Eg. Pressure, volume, temperature, etc.

There are two types of properties:

Extensive property

• Those properties which depend on mass are known as extensive properties.
• Examples are volume, energy, enthalpy, entropy etc.

Intensive property

• Those properties which don't depend on mass are known as intensive properties.
• Examples are pressure, temperature, density, viscosity.

Important Points

• The ratio of two extensive properties is an intensive property.
• Specific properties are intensive properties. For example specific volume, specific energy, specific heat etc.
• If a property divides with space then it is extensive property otherwise the property will be intensive.

here are two thermodynamics functions:

Path function: Heat and work are path functions. Their magnitude depends on the path followed during a process as well as end states.

Point function: Pressure, temperature, volume and internal energy etc. are point function. They depend on the end states only, not on the path followed.

According to first law of thermodynamics:

δQ = δW + ΔU

When a process is executed by a system, the change in stored energy of the system is numerically equal to the net heat interaction minus the net work interaction during the process:

ΔU = δQ – δW where U is the internal energy which is introduced by this law.

And change in internal energy is point function (path-independent) i.e. state function.

Note that Q and W themselves depend on the path followed. But their difference does not.

This implies that the difference between the heat and work interactions during a process is a property of the system.

Explanation:

Properties:

All measurable characteristics of a system are known as properties. Eg. Pressure, volume, temperature, internal energy, density etc.

There are two types of properties:

Total Volume:

• Volume is the amount of space an object takes up, it is denoted by V.
• Volume depends on the mass of the substance as the formula for volume is :

 \(V = {m\over d}\), where m= mass, d = density

• It is thus an extensive property.

Additional Information

Temperature:

• Temperature(T) is the measurement of the heat content of a body.
• Its units are Celcius (ºC), Kelvin (K), Farhenheit (ºF).
• The temperature of a body does not depend on the amount of mass of a substance. If gas has say temperature 288 K, it will mean that every particle of the gas is at temperature 288 K. It is thus an intensive property.
• Hence, the intensive property is Temperature.

​Pressure:

• A container is having pressure P if the container is divided into equal part then the pressure will remain constant.
• So the pressure is an intensive property.

Explanation:

High grade and low-grade energy :

Based on the thermodynamic concepts, an energy source can be called as high-grade or low-grade, depending on the ease with which it can be converted into other forms.

High grade energy:

• The energy which can be completely converted in to other form of energy is known as high grade energy.
• Conversion of high grade energy is exempted from limitation of second law of thermodynamics

Examples of high grade energy:

• Mechanical work 
• Electrical work
• Water power 
• Wind power
• Kinetic energy of jet
• Tidal power

Low grade energy:

• The energy which can not be converted completely in to shaft work is known as low grade energy.
• Conversion of low grade energy is subjected to limitations of second law of thermodynamics.

Examples of low grade energy:

• Heat or thermal energy
• Heat derived from nuclear fission or fusion
• Heat derived from combustion of fossil fuel

Hence work is high grade and heat is low grade energy.

Explanation:

Boundary:

• The thermodynamical system is a body of matter or radiation which is confined in space by walls, which separates it from the surroundings.  

• The system is separated from the surrounding by the boundary. 
• The boundary may be fixed or moveable.
• The different types of thermodynamic boundaries are 
• Diathermic boundary:  This is the type of boundary that allows the flow of heat between the system and surroundings. 
  • A hot cup of Tea is an example of a Diathermic wall.
• Adiabatic boundary: This type of boundary doesn't allow the flow of heat between the system and surroundings.

Concept:

Intensive Property: These are the properties of system which are independent of mass under consideration. For e.g. Pressure, Temperature, density

Extensive Properties: The properties which depend on the mass of system under consideration.

For e.g Internal Energy, Enthalpy, Volume, Entropy

Note: All specific properties are intensive properties. For e.g. specific volume, specific entropy etc.

Explanation:

• There are two types of internal energy of a system i.e. macroscopic and microscopic.
• From a thermodynamic point of view, we will focus on the microscopic approach i.e. at the molecular level.
• The microscopic energy consists of energy at the molecular level e.g. molecular rotation, vibration, etc. and energy at the nuclear level is also involved.
• The rotational and vibrational energy also depends upon the molecular structure e.g. inertia of molecules depends upon how the atoms are arranged.
• So, the internal energy of a system is dependent on molecular structure and the degree of molecular activity. 
• Internal energy is an extensive property, so it depends on mass and volume, hence it depends on molecular weight.

Concept:

The initial condition is P₁, V₁

And the final condition is \({P_2} = \frac{{{P_1}}}{2}\), V₂ = 3V₁

Hyperbolic/Isothermal Process:

T = C i.e. PV = C 

Here: \(P_2V_2=\frac{P_1}{2}(3V_1)\ne P_1V_1\)

Polytropic Process:

PVⁿ = C

\({P_1}V_1^n = {P_2}V_2^n\)

\( \Rightarrow {P_1}V_1^n = \left( {\frac{{{P_1}}}{2}} \right){\left( {3{V_1}} \right)^n }\)

\( \Rightarrow V_1^n = \frac{{{3^n }}}{2}V_1^n \)

⇒ 3ⁿ = 2

⇒ For n < 1 ⇒ n = 0.63

Adiabatic Process:

In adiabatic process, γ = 1.4

Concept:

• The thermodynamical system is a body of matter or radiation which is confined in space by walls, which separates it from the surroundings.  

• The system is separated from the surrounding by the boundary. 
• The different types of thermodynamic boundaries are 
• Diathermic boundary:  This is the type of boundary that allows the flow of heat between the system and surroundings. 
  • A hot cup of Tea is an example of a Diathermic wall.
• Adiabatic boundary: This type of boundary doesn't allow the flow of heat between the system and surroundings.​
• There are 3 types of a thermodynamical system     

1. Open System: The type of system that can exchange heat and temperature with surroundings.
2. Closed System: The type of system in which the exchange of energy is only possible but not matter.
3. Isolated System: The type of system which cannot exchange either matter or energy with its surrounding.

Concept:

Work done by a closed system in an adiabatic process is equal to the internal energy, which is a point function. Also in the case of an adiabatic process for a closed system work is independent of path. 

Joule-Kelvin Effect:

• A graph is made where a gas temperature is recorded at different pressure keeping enthalpy constant.
• A series of the experiment is done with different enthalpy values and temperature, pressure is recorded.
• The curve passing through the maxima of these enthalpies is called the inversion curve.

Inversion Curve:

The numerical value of the slope at any point is called the Joule-Kelvin coefficient (μ_J).

\({\mu _J} = {\left( {\frac{{\partial T}}{{\partial p}}} \right)_h}\)

The curve passing through the maximum temperature in different enthalpies in the temperature-pressure graph is known as Inversion Curve. It is the locus of all points where μ_J is zero.

A liquid expands upon freezing when the slope of its fusion curve on the pressure-temperature diagram is negative.

Entropy change,  \(ds = \frac{{\delta \theta }}{T} + {\left( {{\delta _s}} \right)_{gen}}\)

Now for the Heat rejection process, δQ is negative and \({\left( {{\delta _s}} \right)_{gen}}\)  is positive.

If \(\frac{{dQ}}{T} = {\left( {{\delta _s}} \right)_{gen}}\)  then ds = 0

∴ For an irreversible heat rejection process also, entropy may remain constant.