Problem 19 - Chemistry The Central Science

Question

(a) What is meant by the term system in thermodynamics? (b) What is a closed system? (c) What do we call the part of the universe that is not part of the system?

Step-by-Step Solution

Answer

(a) In thermodynamics, a "system" refers to a specific portion of the universe being observed or studied, surrounded by a boundary separating it from its surroundings. (b) A "closed system" is a type of thermodynamic system that can exchange energy with its surroundings but does not exchange matter. (c) The part of the universe not part of the system being studied is called the "surroundings."

Step 1: (a) Definition of System in Thermodynamics

In thermodynamics, a "system" is a specific portion of the universe that is being observed or studied. It can be any specific region or object, like a container of gas, a metal, or a chemical reaction. The system is surrounded by a boundary that separates it from its surroundings (the rest of the universe). The boundary could be physical or imaginary. The main focus of the thermodynamic analysis is on the internal processes and properties of the system.

Step 2: (b) Definition of Closed System

A "closed system" is a type of thermodynamic system that can exchange energy (in the form of work and heat) with its surroundings but does not exchange matter. In other words, no mass or particles can move across the boundary, and the total amount of matter within the closed system remains constant during the process.

Step 3: (c) Name for the Part of the Universe Not Part of the System

The part of the universe that is not part of the system being studied is called the "surroundings." In thermodynamic analysis, the surroundings include everything that is outside the system, encompassing the rest of the universe. Both the system and its surroundings together constitute the "universe" in a thermodynamic context.

Key Concepts

Thermodynamic System

In thermodynamics, the term "system" refers to a specific part of the universe that is under study or consideration. It can be anything from a container of gas to a piece of metal or a chemical reaction. The system includes all the components or substances being analyzed, and is separated from its surroundings by a boundary. This boundary can be either physically tangible, like the walls of a container, or simply an imaginary demarcation used for theoretical purposes.

The concept of a system is crucial because it allows scientists and engineers to focus on the internal processes and transformations that occur within it. This focus is essential for analyzing how energy is transferred and transformed within the system, as well as how it interacts with the surroundings.

Closed System

A closed system in thermodynamics is one that can exchange energy in the form of heat or work with its surroundings, but does not allow the transfer of matter. In simpler terms, the amount of substance or material within the system stays constant over time. This feature makes closed systems particularly interesting when examining energy conversions and transfers.

A familiar example of a closed system could be a sealed container of gas where no particles enter or leave, but the container itself can be heated from outside or exert force against a piston. Because mass remains unchanged in closed systems, these models help us understand processes where conservation of energy is key.

Surroundings in Thermodynamics

In the context of thermodynamics, the "surroundings" represent everything outside of the system being studied. Essentially, it is the remainder of the universe that interacts with the system across its boundary. The surroundings play a vital role because they are where exchanges of energy and sometimes matter occur.

When a system undergoes a thermodynamic process, energy (in various forms) can cross the boundary, influencing both the system and its surroundings. Understanding this interaction is crucial for analyzing energy efficiency, predicting system behavior, and designing practical systems in engineering. It's important to note that in a thermodynamic framework, the system and its surroundings together form what is referred to as the "universe."