Thermodynamics Basics Quiz

Thermodynamics

Thermodynamics is a branch of physics that deals with the relationship between heat, work, and energy. It focuses on how energy moves between systems, usually between substances that are in contact with each other. The most fundamental laws of thermodynamics establish constraints on the energy transfer and transformations within isolated systems. These principles govern both the natural world and human creations such as engines and refrigerators.

Laws of Thermodynamics

There are four main laws of thermodynamics:

Zeroth law: If two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.

First law: This law establishes the principle of conservation of energy. Energy cannot be created or destroyed, only transferred from one place to another or transformed into different forms.

Second law: Also known as the law of entropy, it states that under the assumption of no external work being done by the system, the total entropy of an isolated system cannot decrease over time. Entropy is a measure of disorder in a system.

Third law: This law defines the entropy of a perfect crystal (a system of atoms vibrating in a regular lattice) at absolute zero temperature as being exactly zero.

Thermodynamic Processes

Thermodynamics can be applied to different types of processes, such as:

Isothermal process: A thermodynamic process that occurs at constant temperature.

Adiabatic process: A thermodynamic process in which there is no heat exchange with the environment.

Heat Engines

A heat engine is a device that converts thermal energy into mechanical work. The most common example of this is a steam engine, which uses energy from burning coal to produce motion. There are two essential parts to any heat engine: a source of heat that provides the working substance with energy, and a mechanism for doing work on the surroundings.

Entropy

Entropy is a property related to the degree of disorder or randomness in a system. It is often used to describe systems with many particles interacting with each other. When something changes, and part of it becomes more disordered, then entropy has increased. For example, when you mix hot water with cold water, the overall temperature goes down but the heat spread out so it got dispersed over larger volume of mixture, resulting in an increase in entropy.

Enthalpy

Enthalpy is a thermodynamic potential that measures the maximum reversible work that can be done by a system at constant temperature and pressure. It is given by the sum of product of partial pressures and their respective entropies or molar volumes: H = pV = TΔS.