What are reactive processes?

Reactive processes are the processes in which any reaction occurs. The reactions can be any combination reaction, decomposition reaction, combustion reaction, oxidation reaction, reduction reaction, neutralization reaction, displacement reaction, or double displacement reaction.

Types of systems in a reactive process

The chemical reactions occur in any of the three kinds of systems: closed system, open system, an isolated system.

Closed system

In a closed system, the material can neither come inside the system nor can leave the system. A closed system is often confined using the walls so that the matter cannot cross the boundary of the system. The energy (heat in most cases), however, can be exchanged between the surroundings and the system in a closed system.

Open system

In an open system, the material and energy both can be exchanged between the system and the surrounding. An open system allows the matter and energy to cross the boundary of the system.

Isolated system

In an isolated system, neither the matter nor the energy can be exchanged between the system and the surrounding. An isolated system restricts all the matters, energy, and radiation to cross the system boundary. It comprises the walls that are made non-conductive to the heat, impermeable to all kinds of matters, and reflective to all kinds of radiations.

Material Balance

Material balance is a fundamental part of any industry that controls the processes of an industry. The concept of material balance is derived from the law of conservation of mass. As per the law of conservation of mass, mass can neither be created nor be destroyed but is transformed from one form to another. Thus, the total quantity of mass entering the system will be equal to that of the total quantity of mass exiting the system. Similarly, the total amount of material entering a system will be equal to the total amount of material exiting the system and stored in it. Mathematically, this can be stated as,

Material In = Material Out + Material Stored

The input material for any system will be a raw material and the output material will be the products along with the wastes. Hence, the above equation can also be stated as,

Raw Materials = Products + Wastes + Materials stored + Losses

Before writing a material balance equation, the type of process taking place in a system needs to be identified. The various types of processes that take place in a system are batch, continuous, semi-batch, steady-state, and transient. A batch process is a process in which the materials are not allowed to transfer into the system or out of the system. A continuous process is a process in which the materials are allowed to transfer in and out of the system continuously. A semi-batch process is a process that is neither batch nor continuous process. A steady-state process is a process in which the process variables do not change with time. A transient process is a process in which the process variable change with time.

Energy Balance

Energy balance is also an important feature of a process taking place in a system. It is the same as that of the material balance. The total energy entering a system will be equal to the total energy stored in a system and the total energy exiting the system. Mathematically, it can be represented as:

Energy In = Energy Out + Energy Stored

The above formula can be elaborated as-

E_R = E_P + E_W + E_L + E_S

Where E_R is the energy entering the system, E_P is the energy leaving with the product, E_W is the energy leaving with the waste material, E_L is the energy lost to the surrounding, and E_S is the energy stored in the system.

Context and Applications

The concept of reactive processes is widely used by chemical engineers on daily basis in the industries carrying out the chemical engineering process. It is also used in day-to-day life in various things such as filling the tire with air, which is an example of an open system and semi-batch process, water flowing through a pipe is an example of an open system and continuous process. The reactive processes are useful for the students undergoing courses such as Bachelor of Engineering or Technology (Chemical) and Master of Technology (Chemical, Petroleum, Oil).

Practice Problems

1. Which of the following are the processes in which any reaction occurs?

a) Reactive processes

b) Physical processes

c) Topographic processes

d) Celestial processes

Answer – a

Explanation – The reactive processes are the processes in which any reaction occurs. Physical, topographical, and celestial processes are not the processes in which any chemical reaction occurs.

2. Which of the following is not a type of reaction?

a) Combination reaction

b) Decomposition reaction

c) Combustion reaction

d) Penta-displacement reaction

Answer – d

Explanation – A Penta-displacement reaction is not a type of reaction. Combination reaction, decomposition reaction, and combustion reaction are the types of reactions.

3. Which of the following is not a type of system?

a) Open system

b) Closed system

c) Vacuumed system

d) Isolated system

Answer – c

Explanation – A vacuumed system is not a type of system. Open, system, closed system, and isolated system are the types of systems in which reactions take place.

4. Which of the following is not a type of process that takes place in a system?

a) Batch process

b) Exchanger process

c) Continuous process

d) Semi-batch process

Answer – b

Explanation – An exchanger process is not a type of process that takes place in a system. Batch process, continuous process, and semi-batch process are the types of processes

5. In which of the following systems, the material can neither come inside the system nor can leave the system?

a) Closed system

b) Open system

c) Isolated system

d) Vacuum system

Answer – a

Explanation – In a closed system, the material can neither come inside the system nor can leave the system. Therefore it is termed as a closed system.