Name: entropy and spontaneous change
Uploaded: 2023-04-30T10:08:43.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions Energy and Dynamics

9-12.EVS.1.1

The Second Law of Thermodynamics

Die Entropie, abgekürzt als S, ist das thermodynamische Maß für Unordnung oder Zufälligkeit. Systeme mit mehr Unordnung haben eine höhere Entropie als solche mit weniger Unordnung.
Zum Beispiel hat eine ungefaltete Aminosäurekette eine höhere Entropie als wenn die Kette richtig gefaltet ist, da die lineare Kette flexibler und unorganisierter ist als ein dicht gepacktes Protein.
Der zweite Hauptsatz der Thermodynamik besagt, dass die Entropie eines isolierten Systems immer zunimmt. Das bedeutet, dass ohne Input von außen alles ungeordneter wird.
Isolierte Systeme kommen in der Natur selten vor, daher untersucht die Thermodynamik oft die Änderung der Entropie des gesamten Universums. Die Änderung der Entropie des Universums umfasst sowohl Entropieänderungen des untersuchten Systems als auch seiner Umgebung.
Ein Prozess, bei dem die Entropie des Universums zunimmt, d.h. ein Prozess, der ein ΔS größer als Null hat, findet spontan statt. Ein Prozess, bei dem die Entropie abnimmt oder ein -ΔS hat, ist nicht spontan und erfordert Energiezufuhr, um zu erfolgen.

der zweite hauptsatz der thermodynamik

Auf der Suche nach einer Eigenschaft, die die Spontaneität eines Prozesses zuverlässig vorhersagen kann, wurde ein vielversprechender Kandidat identifiziert: die Entropie. Wissenschaftler bezeichnen das Maß für Zufälligkeit oder Unordnung innerhalb eines Systems als Entropie. Hohe Entropie bedeutet hohe Unordnung und niedrige Energie. Um die Entropie besser zu verstehen, denken Sie an das Schlafzimmer eines Studenten. Wenn keine Energie oder Arbeit hineingesteckt würde, würde der Raum schnell unordentlich werden. Es würde in einem sehr ungeordneten Zustand mit hoher Entropie existieren. Es muss Energie in das System gesteckt werden, indem der Schüler arbeitet und alles wegräumt, um den Raum wieder in einen Zustand der Sauberkeit und Ordnung zu bringen. Dieser Zustand weist eine niedrige Entropie auf.

Prozesse, die mit einer Entropiezunahme des Systems einhergehen (ΔS > 0), sind sehr oft spontan; Es gibt jedoch zahlreiche gegenteilige Beispiele. Indem wir die Betrachtung von Entropieänderungen auf die Umgebung ausweiten, können wir zu einer wichtigen Schlussfolgerung hinsichtlich der Beziehung zwischen dieser Eigenschaft und der Spontaneität gelangen. In thermodynamischen Modellen umfassen das System und die Umgebung alles, also das Universum, und daher gilt Folgendes:

Δ_Suniv = Δ_Ssys + Δ_Ssurr

Der zweite Hauptsatz der Thermodynamik besagt, dass alle spontanen Veränderungen eine Zunahme der Entropie des Universums bewirken. Eine Zusammenfassung der Beziehung zwischen Entropie und Spontaneität des Prozesses ist in Tabelle 1 gegeben.

Tabelle 1: Zusammenhang zwischen der Entropie und der Spontaneität des Prozesses.

<table style="border-collapse: collapse; border: 1px solid black;">
	<tbody>
		<tr>
			<td style="border: 1px solid black; padding: 5px;">ΔSuniv > 0</td>
			<td style="border: 1px solid black; padding: 5px;">spontan</td>
		</tr>
		<tr>
			<td style="border: 1px solid black; padding: 5px;">ΔSuniv < 0</td>
			<td style="border: 1px solid black; padding: 5px;">nicht spontan (spontan in entgegengesetzter Richtung)</td>
		</tr>
		<tr>
			<td style="border: 1px solid black; padding: 5px;">ΔSuniv = 0</td>
			<td style="border: 1px solid black; padding: 5px;">im Gleichgewicht</td>
		</tr>
	</tbody>
</table>

Dieser Text ist adaptiert von Openstax, Biology 2e, <a href="https://openstax.org/books/biology-2e/pages/6-3-the-laws-of-thermodynamics">Section 6.3: The Laws of Thermodynamics</a> und Openstax, Chemie 2e, <a href="https://openstax.org/books/chemistry-2e/pages/16-3-the-second-and-third-laws-of-thermodynamics">16.3 The Second and Third Laws of Thermodynamics.</a>

Der Zweite Hauptsatz der Thermodynamik

Auf der Suche nach einer Eigenschaft, die die Spontaneität eines Prozesses zuverlässig vorhersagen kann, wurde ein vielversprechender Kandidat identifiziert: die Entropie. Wissenschaftler...

Education

Lehre

JoVE Core

Cell Biology

Zellbiologie

Unit 1

Einheit 1

Energy and Catalysis

Energie und Katalyse

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

entropy and spontaneous change

Entropy helps predict whether a process will happen on its own. Entropy is a measure of randomness or disorder in a system. High entropy means high disorder and low energy. A student’s bedroom is a simple example. If no work is done, the room becomes messy over time. That messy state is highly disordered and has high entropy. To make the room clean again, energy must be added as the student puts things away. That organized state has low entropy.

Processes that increase the entropy of the system, written as ΔS &gt; 0, are often spontaneous. Spontaneous means a process can occur without outside help. However, there are many exceptions. To understand spontaneity more fully, entropy changes in the surroundings must also be included. In thermodynamic models, the system and its surroundings make up the universe. The total change in entropy is written as ΔSuniv = ΔSsys + ΔSsurr.

The second law of thermodynamics connects entropy with spontaneous change. It states that all spontaneous changes increase the entropy of the universe. If ΔSuniv is greater than 0, the process is spontaneous. If ΔSuniv is less than 0, the process is nonspontaneous, although the opposite direction would be spontaneous. If ΔSuniv equals 0, the system is at equilibrium.

Entropy and Spontaneous Change

the first law of thermodynamics

Energy Changes in Cells and Matter

The first law of thermodynamics describes how energy changes form in the universe. The total amount of energy stays constant. Energy can move from one place to another or change into a different form, but it cannot be created or destroyed. These energy changes happen in everyday life. A light bulb changes electrical energy into light energy. A gas stove changes chemical energy in natural gas into heat energy. Plants also carry out a major energy transformation when they convert sunlight energy...

the second law of thermodynamics

Entropy helps predict whether a process will happen on its own. Entropy is a measure of randomness or disorder in a system. High entropy means high disorder and low energy. A student’s bedroom is a simple example. If no work is done, the room becomes messy over time. That messy state is highly disordered and has high entropy. To make the room clean again, energy must be added as the student puts things away. That organized state has low entropy. Processes that increase the entropy of the...

enthalpy within the cell

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entropy within the cell

Cell Energy Loss and Entropy

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an introduction to free energy

Gibbs Free Energy and Reaction Work

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the equilibrium binding constant and binding strength

the-equilibrium-binding-constant-and-binding-strength

How Equilibrium Binding Constant Affects Binding

The equilibrium binding constant describes how strongly two molecules bind at equilibrium. It is a useful way to compare binding strength in molecular interactions. This topic focuses on how binding is measured and what the equilibrium binding constant means. A higher value indicates stronger binding, while a lower value indicates weaker binding. Understanding this constant helps explain how tightly molecules stay together under equilibrium conditions. The page also connects the binding...

free energy and equilibrium

Free Energy and Reaction Direction

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non-equilibrium in the cell

Cells Stay Out of Equilibrium

Cells stay out of chemical equilibrium by constantly using energy and moving materials in and out. Chemical reactions in metabolism are often reversible. They can go in both directions. In one direction, they release energy to the surroundings. In the reverse direction, they absorb energy. The same idea applies to reactions that build and break down cell molecules. Proteins, for example, can be broken into individual amino acids, and amino acids can be used to build proteins again. In a closed...

oxidation and reduction of organic molecules

oxidation-and-reduction-of-organic-molecules

Electron Carriers in Cell Energy Transfer

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Enzyme Function, Cofactors, and Inhibitors

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enzymes and activation energy

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Graphing Enzyme Kinetics Data

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How Fast Enzymes Work in Digestion

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catalytically perfect enzymes

Diffusion-Controlled Enzymes and Reaction Speed

Catalytically perfect enzymes are enzymes that speed up biochemical reactions at very high rates. The idea was first proposed by W. J. Albery and J. R. Knowles in 1976. These enzymes have catalytic efficiency values of about 10^8 to 10^9 M^-1 s^-1 and are also called diffusion-controlled enzymes because diffusion of the substrate into the active site is the only rate-limiting step. Examples of catalytically perfect enzymes include triose phosphate isomerase, fumarase, and superoxide dismutase.

introduction to mechanisms of enzyme catalysis

introduction-to-mechanisms-of-enzyme-catalysis

How Enzymes Change Shape to Catalyze

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ligand binding and linkage

Ligand Binding and Allosteric Effects

Ligand binding and linkage describe how one molecule can affect another when it binds to a protein. In this topic, the focus is on how binding at one site can influence activity at a different site on the same protein. This idea is important for understanding protein function in high school biology. It helps explain why some proteins respond more strongly after a ligand attaches. The transcript centers on the connection between ligand binding and linkage, which is a key concept in molecular...

cooperative allosteric transitions

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atp and macromolecule synthesis

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coupled reactions

ATP Powers Cellular Work

ATP powers many kinds of cellular work by coupling energy-releasing reactions to energy-requiring ones. Some reactions happen on their own and release energy. Others need an energy input to move forward. Cells link these reactions so important processes can still occur. Adenosine triphosphate, or ATP, stores energy that cells can use quickly. ATP hydrolysis is the breaking of ATP, and it releases energy. Cells often use that released energy to drive endergonic reactions, which are reactions...

key terms and concepts

Learn how entropy relates to spontaneous change, why disorder matters, and how system and surroundings determine whether a process is spontaneous.

Entropy and Spontaneous Change | JoVE K12

cell biology

JoVE Core Zellbiologie veranschaulicht komplexe zelluläre Prozesse in leicht verständlichen und dennoch umfassenden animierten Videolektionen. Diese Sammlung konzentriert sich auf die wesentlichen Bestandteile und Funktionen von Zellen, einschließlich Organellen und Membranen, Zelltransport und Zellenergie. Ergänzt wird sie durch Videos von Wissenschaftlern in Aktion, die die Anwendung der Zellbiologie in realen Forschungsexperimenten demonstrieren.

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9-12.EVS.1.2

Entropy and Spontaneous Change

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