THERMODYNAMICS PDF
THERMODYNAMICS PDF
Introduction
Chemical thermodynamics deals with the relationship between various forms of energy in a process. Thermodynamics deals with macroscopic properties. This chapter introduces a major subsidiary thermodynamic property, the Gibbs free energy which lets us express the spontaneity of a process in terms of the properties of the system. This chapter helps to explain why gases expand or diffuse.
System and Surrounding
1. System: A specific portion of the universe under study that is separated from the rest of the universe with a boundary is called a system.
2. Surroundings: The rest of the universe which might be in a position to exchange energy and matter with the system is known as the surrounding.
Types of System:
1. Open system: A system can be open if it can exchange both energy and matter with its surroundings.
2. Closed system: The system can be closed if it can exchange energy but not matter with surroundings.
3. Isolated system: A system can be isolated if it can neither exchange energy nor matter with its surroundings.
Extensive Properties
The properties which depend upon the mass of the substance are known as extensive properties i.e., mass, volume, internal energy, enthalpy, etc.
Intensive Properties
The properties which are independent of mass of the substance are known as intensive properties i.e., temperature, pressure, density, and refractive index.
Thermodynamic State of a System
A state is the condition of a system as specified by its physical properties. We can describe the state of a gas by quoting its pressure (p), volume (V), temperature (T), amount (n) etc. Variables like p, V, and T are called state variables or state functions because their values depend only on the state of the system and not on how it is reached.
State Functions
The thermodynamic parameters which depend only on initial and final states of the system are known as a state function. i.e., internal energy(E), Enthalpy (H), entropy (S), Gibb’s free energy (G).
Path Functions
The thermodynamic parameters where value does not depend merely on the initial and final state but depends upon the path followed is known as path function. i.e., heat (q), work done (W).
Thermodynamic Process
The sequence followed to change one thermodynamic state of a system into another is called the thermodynamic process. The types of thermodynamic processes are:
1. Isothermal process: It is the process in which temperature is kept constant means the temperature of the initial and final state of the system along with the entire path of the process is the same.
2. Isobaric process: It is the process in which pressure is kept constant for the entire process.
3. Isochoric process: It is the process in which volume is kept constant.
4. Adiabatic process: The process in which heat transaction across boundaries is not allowed.
5. Reversible process and Irreversible process: In thermodynamics, a process is said to be reversible when energy change in each step of the process can be reversed by changing the variables such as pressure, volume, or temperature acting on them. In such a process, the driving and opposing forces differ infinitesimally and the process can be reversed completely by increasing the opposing force by an infinitesimally small amount.
Any process that does not take place in the above-mentioned manner is said to be an irreversible process. In an irreversible process, the driving and opposing forces differ by a large amount.
6. Cyclic process: It is the process that runs in a close loop means a process in which initial and final states are identical.
THERMODYNAMICS PDF
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