ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Thermodynamics: A Beginners Guide

Updated on January 30, 2018

A basic easy learning and revision guide to Thermodynamics. I’ve tried to make this article easy to follow by using my own learning techniques i.e. very simple and without repetition.

The Basics

● Thermodynamics in its simplest definition is; the study of HEAT (thermo) and MOVEMENT (dynamics).

● Thermodynamics is a branch of physics associated with the flow of HEAT and ENERGY into or out of a SYSTEM as it undergoes physical or chemical change.

● Any “SYSTEM” can be classed as a SOLID, a LIQUID or a GAS.

● The Laws of Thermodynamics describe accepted physical quantities that define thermodynamic systems.

● These physical quantities are; ENERGY, ENTROPY and TEMPERATURE.

● The Laws of Thermodynamics govern the DIRECTION of a spontaneous process.

● If enough separate interactions are involved then the DIRECTION will ALWAYS be towards increased ENTROPY.

● If you increase the HEAT in any system what you are actually doing is increasing the ENERGY in the system. i.e. HEAT = ENERGY.

The Four Laws of Thermodynamics

THE ZEROTH LAW

● It is called the ZEROTH law because it was developed after the first and second laws had already been established and named.

● It was considered more important so it was given a lower number.

● When two systems are in thermal equilibrium with a third system then those two systems are in thermal equilibrium with each other.

THE FIRST LAW (ENERGY > E)

● The First Law is also known as the LAW OF CONSERVATION OF ENERGY.

● This specifies that energy CANNOT be created or destroyed in an isolated system.

● It states that energy can only be transferred or changed from one form to another.

● There are two types of processes: HEAT and MOVEMENT (WORK) that can lead to an alteration in the internal energy of a system.

THE SECOND LAW (ENTROPY > S)

● The Second Law represents the amount of energy in a system’s thermal energy per unit of temperature that is no longer available to convert into useful work.

● Usually defined as the degree of DISORDER or RANDOMNESS in the system.

● The more disordered a substance is then the GREATER the Entropy.

● This specifies that the Entropy of any isolated system ALWAYS increases with time OR remains constant.

● The Entropy of a system increases when there are more available MICROSTATES.

● The Entropy of a substance at 1 atmospheric (atm) pressure determines if a reaction will take place spontaneously.

● Entropies typically INCREASE with molecular weight.

● The Entropy of a solid is LESS than that of a liquid which is LESS than a gas.

● It is also a measure of the here and now RANDOM activity in a system. How long it took and how many changes were involved to get to the present is not important.

THE THIRD LAW (TEMPERATURE > T)

● The Third Law states that the ENTROPY of a system will approach a constant value as the temperature nears ABSOLUTE ZERO.

● The Entropy of a perfect crystal at ABSOLUTE ZERO is exactly EQUAL to ZERO.

Spontaneous and Non-Spontaneous (ENDERGONIC) Processes

● A SPONTANEOUS process is capable of moving in a given direction WITHOUT needing to be influenced by an outside source of energy.

● Spontaneous processes are also called NATURAL processes and depending on the process can happen very quickly or take millions of years.

● A NON-SPONTANEOUS (Endergonic) reaction is a chemical reaction in which the normal change in free energy is positive and energy is absorbed.

Thermodynamic Systems

● A thermodynamic system is one that INTERACTS and EXCHANGES energy with the area around it.

ADIABATIC: describes a system that changes with no transfer of heat in or out.

ISOBARIC: describes a system that changes but the pressure stays constant.

ISOTHERMAL: describes a system that changes in every way but the temperature stays constant.

ISOVOLUMIC: describes a system that changes but the volume stays constant.

Some Helpful Facts

● The definition of ABSOLUTE ZERO is: The COLDEST temperature that is theoretically possible.

● The definition of ENDERGONIC is: A reaction that absorbs energy FROM its surroundings.

● The definition of EXERGONIC is: A reaction that releases energy INTO its surroundings.

● The definition of a MICROSTATE is: The description of a system that depends on the states of each element of that system.

● Energy can be shared between MICROSTATES of a system.

● All parts of the Universe that are NOT within the THERMODYNAMIC SYSTEM of interest are known as SURROUNDINGS.

● The term REVERSIBILITY is used to describe systems that are in equilibrium (i.e. balance) with themselves and the environment around them. A change in one direction will be balanced by an equal change in the opposite direction.

● Zones of HIGH temperatures give off energy to zones with LOWER temperatures.

● Heat will always move from a high to a lower temperature. A HEAT SOURCE is the area where you will find a HIGHER temperature. A HEAT SINK is the area you will find a LOWER temperature.

● ENTHALPY is a measure of the heat content of a CHEMICAL or PHYSICAL system. Therefore a change in heat will be an ENTHALPY CHANGE.

A Final Thought

Trying to put even the basics of Thermodynamics and its Laws into easy to understand (by me) bite-sizes tested my rudimentary writing skills to the limit.

If you are studying and learning all about the Thermodynamics then good on you and I wish you well.

If there are any mistakes please let me know.

© 2018 Brian OldWolf

Comments

    0 of 8192 characters used
    Post Comment

    • World Earth profile imageAUTHOR

      Brian OldWolf 

      7 months ago from Old Wolf Cottage

      Thanks Larry. Much appreciated.

    • Larry Rankin profile image

      Larry Rankin 

      7 months ago from Oklahoma

      Very educational and nicely laid out.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)