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

S로 약칭되는 엔트로피는 무질서 또는 임의성의 열역학적 척도입니다. 무질서가 많은 시스템은 무질서가 적은 시스템보다 엔트로피가 더 높습니다.
예를 들어, 풀린 아미노산 사슬은 선형 사슬이 단단히 채워진 단백질보다 더 유연하고 조직화되지 않기 때문에 사슬이 적절하게 접혀 있을 때보다 더 높은 엔트로피를 갖습니다.
열역학 제2법칙은 고립된 시스템의 엔트로피가 항상 증가한다는 것입니다. 이것은 외부의 개입 없이 모든 것이 더 무질서해진다는 것을 의미합니다.
고립된 시스템은 자연적으로 발생하는 경우가 거의 없기 때문에 열역학은 종종 전체 우주의 엔트로피 변화를 조사합니다. 우주의 엔트로피 변화에는 연구 중인 시스템과 그 주변의 엔트로피 변화가 모두 포함됩니다.
우주의 엔트로피가 증가하는 과정, 즉 ΔS가 0보다 큰 과정이 자발적으로 발생합니다. 엔트로피가 감소하거나 -ΔS를 갖는 과정은 자발적이지 않으며 발생하기 위해 에너지 입력이 필요합니다.

열역학 제2법칙

프로세스의 자발성을 확실하게 예측할 수 있는 속성을 식별하는 과정에서 유망한 후보인 엔트로피가 식별되었습니다. 과학자들은 시스템 내 무작위성 또는 무질서의 척도를 엔트로피라고 부릅니다. 엔트로피가 높다는 것은 무질서도가 높고 에너지가 낮다는 것을 의미합니다. 엔트로피를 더 잘 이해하려면 학생의 침실을 생각해 보세요. 에너지나 노력을 들이지 않으면 방은 금방 지저분해질 것입니다. 그것은 매우 무질서한 상태, 즉 높은 엔트로피 상태로 존재할 것입니다. 방을 깨끗하고 질서 있는 상태로 되돌리기 위해서는 학생이 일을 하고 모든 것을 치우는 형태로 시스템에 에너지가 투입되어야 합니다. 이 상태는 엔트로피가 낮은 상태 중 하나입니다.

시스템의 엔트로피 증가(ΔS > 0)를 포함하는 과정은 매우 자발적입니다. 그러나 그 반대의 예는 많습니다. 주변 환경을 포함하도록 엔트로피 변화에 대한 고려를 확장함으로써 우리는 이 속성과 자발성 사이의 관계에 관해 중요한 결론에 도달할 수 있습니다. 열역학 모델에서는 계와 주변 환경이 모든 것, 즉 우주를 구성하므로 다음이 성립합니다.

ΔS_univ = ΔS_sys + ΔS_surr

열역학 제2법칙은 모든 자발적인 변화가 우주의 엔트로피를 증가시킨다고 말합니다. 프로세스의 엔트로피와 자발성 사이의 관계에 대한 요약이 표 1에 나와 있습니다.

표 1: 프로세스의 엔트로피와 자발성 사이의 관계.

<table style="border-collapse: collapse;">
	<tbody>
		<tr>
			<td style="border:1px solid #000; padding:6px 10px;">ΔSuniv > 0</td>
			<td style="border:1px solid #000; padding:6px 10px;">자발적</td>
		</tr>
		<tr>
			<td style="border:1px solid #000; padding:6px 10px;">ΔSuniv < 0</td>
			<td style="border:1px solid #000; padding:6px 10px;">비자발적 (반대 방향으로 자발적)</td>
		</tr>
		<tr>
			<td style="border:1px solid #000; padding:6px 10px;">ΔSuniv = 0</td>
			<td style="border:1px solid #000; padding:6px 10px;">평형 상태</td>
		</tr>
	</tbody>
</table>

이 텍스트는 Openstax, Biology 2e에서 가져온 것입니다, <a href="https://openstax.org/books/biology-2e/pages/6-3-the-laws-of-thermodynamics">Section 6.3: The Laws of Thermodynamics</a> 그리고 Openstax, Chemistry 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>

프로세스의 자발성을 안정적으로 예측할 수 있는 속성을 식별하기 위한 탐구에서 유망한 후보인 엔트로피가 확인되었습니다. 과학자...

Education

교육

JoVE Core

Cell Biology

세포생물학

Unit 1

제1단원

Energy and Catalysis

에너지 및 촉매

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

Cellular Enthalpy and Energy Changes

Cellular enthalpy describes how heat and energy change during chemical and physical processes. Enthalpy is written as H and is defined as the sum of a system’s internal energy, U, and the product of pressure and volume, PV. It is a state function, which means its value depends on the state of the system, not the path taken. Scientists cannot measure the enthalpy of a single substance directly. They can determine enthalpy changes, or ΔH, for a process instead. For reactions or changes that...

entropy within the cell

Cell Energy Loss and Entropy

Cell energy loss and entropy explain why living things need constant energy input. Cells obtain energy, transform it, and use it to do work, but these transfers are never completely efficient. In each transfer, some energy is lost in a form that cannot be used. In many cases, that lost energy is heat energy.

an introduction to free energy

Gibbs Free Energy and Reaction Work

Gibbs free energy describes the usable energy in a chemical reaction. It helps scientists compare how much energy different reactions release. This measurement is called Gibbs free energy, or G, after Josiah Willard Gibbs. The second law of thermodynamics explains why not all energy stays available for work. Some energy is lost in an unusable form, such as heat, and this loss increases entropy. Gibbs free energy is the energy left after that entropy loss is taken into account. Every chemical...

endergonic and exergonic reactions in the cell

endergonic-and-exergonic-reactions-in-the-cell

Cell Reactions That Release or Store Energy

Cell reactions can either release energy or store it for later use. In chemistry, this difference is described by the value of ΔG, or free energy change. When energy is released during a reaction, ΔG is negative. The products then have less free energy than the reactants because some free energy has been given off. Reactions with a negative ΔG are called exergonic reactions. Exergonic means energy is leaving the system. These reactions are also called spontaneous reactions because they can...

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

Free energy and reaction direction are linked in chemical equilibrium. A free energy change, ΔG, shows the driving force for a process. When ΔG is negative, the process is driven forward. When ΔG is positive, the reverse direction is favored. When ΔG is zero, the forward and reverse driving forces are equal, and the system is at equilibrium. The reaction quotient, Q, helps show how close a system is to equilibrium. Q is the numerical value of the mass action expression for the system. It can...

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

Cell energy production depends on redox reactions, which are oxidation and reduction reactions that happen together. In oxidation, an electron is removed from an atom in a compound. In reduction, that same electron is added to another compound. Because these reactions usually occur as a pair, they are called redox reactions. When a molecule loses an electron, its potential energy goes down. The electron does not stay free in the cytoplasm. Instead, it moves to a second compound and reduces...

introduction to enzymes

Enzyme Function, Cofactors, and Inhibitors

Enzymes are proteins that speed up biochemical reactions without being used up. Humans have used enzymes since about 7000 BCE, when they fermented sugars to make alcohol without knowing the reaction was enzyme-catalyzed. The word enzyme was coined by Wilhelm Kuhne in 1877. It comes from the Greek words en, meaning “in” or “within,” and zyme, meaning “yeast.” Enzymes work through active sites, which are regions that bind substrates and help convert them into products. Many enzymes also have...

enzymes and activation energy

How Enzymes Lower Reaction Energy

Enzymes lower the energy needed for a chemical reaction to begin. That starting energy is called activation energy, or free energy of activation, and it is often written as Ea. During a reaction, bonds break and new bonds form. In glucose breakdown, for example, bonds between carbon atoms break and release energy because they are energy-storing bonds. Before a reaction can move forward, reactant molecules must reach a high-energy, unstable shape called the transition state. To get there, the...

introduction to enzyme kinetics

Graphing Enzyme Kinetics Data

Enzyme kinetics uses graphs to show how fast a biochemical reaction happens. Scientists measure the initial reaction rate, or velocity (Vo), at different substrate concentrations ([S]). They may also run trials with inhibitors or other molecules that change the reaction rate. The results are often plotted as Vo against [S]. For many single-substrate reactions, the data fits the Michaelis-Menten equation. This equation, named after Leonor Michaelis and Maud Menten, helps estimate the maximum...

turnover number and catalytic efficiency

How Fast Enzymes Work in Digestion

Enzymes can work at very different speeds, and their turnover number shows how fast they convert substrate molecules into products. Turnover number is the maximum number of substrate molecules an enzyme can transform per unit time. For most enzymes, this value is between 1 and 1000 molecules per second. Some enzymes are especially fast. Catalase has the highest known turnover number and can convert up to 2.8×10^6 molecules of hydrogen peroxide into water and oxygen each second. Lysozyme has...

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

Enzyme catalysis depends on how enzymes bind substrates and how the active site responds during the reaction. Scientists once described this process with a simple lock-and-key model, where the enzyme and substrate fit together in one instant. Research now supports induced fit, a more dynamic model in which binding causes a small change in the enzyme’s shape. That shift helps create an ideal match between the enzyme and the substrate’s transition state, which improves catalysis. The active site...

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

How Proteins Shift Shape Together

Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule. These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules. Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger...

ribozymes

Catalytic RNA: Ribozymes in Action

Ribozymes are RNA molecules that can act as enzymes. They help speed up specific chemical reactions without being protein enzymes. This makes them an important example of RNA with more than one job in the cell. Some ribozymes can cut RNA molecules, and others can join them together. This shows that RNA can do catalytic work as well as carry genetic information. Ribozymes are a key part of how scientists think about the many roles of RNA in biology. One well-known ribozyme is ribonuclease P,...

atp energy storage and release

ATP Powers Cellular Transport and Reactions

ATP powers cellular transport and many reactions by transferring energy through phosphorylation. ATP is a highly unstable molecule. If it is not used quickly, it breaks down into ADP and inorganic phosphate, and the released energy is lost as heat. Cells use ATP through energy coupling. This means the exergonic reaction of ATP hydrolysis is linked to an endergonic reaction so the reaction can move forward. One major example is the sodium-potassium pump, a transmembrane ion pump that is vital...

atp and macromolecule synthesis

ATP in Building Cell Macromolecules

ATP helps cells build biological macromolecules. These organic compounds are mainly made of carbon atoms bonded to hydrogen, oxygen, nitrogen, and small amounts of other elements. The four major classes of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Most macromolecules start as small subunits called monomers. Cells join monomers with covalent bonds to make larger molecules called polymers. This building process needs energy, so cells depend on ATP, the...

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 Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

The First Law of Thermodynamics

The first law of thermodynamics deals with the total amount of energy in the universe. It states that this total amount of energy is constant. In other ...

In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Scientists ...

Trophic Levels

All organisms in an ecosystem occupy a trophic level in the food chain. The lowest level consists of primary producers, which synthesize their food from ...

Production Efficiency

Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic rates ...

Trophic Efficiency

Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss as ...

1. Use mathematical representations to illustrate how the first two laws of thermodynamics demonstrate energy transfers throughout ecosystems, including food chains, food webs, and trophic levels, at various levels of biological organization.

What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

The Water Cycle

The Earth&rsquo;s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, ...

The Carbon Cycle

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

The Nitrogen Cycle

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of ...

The Phosphorus Cycle

Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, ...

The Sulfur Cycle

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the ...

2. Obtain, evaluate, and communicate information to model the cycling of matter through the biosphere, atmosphere, hydrosphere, and geosphere, including the flow of carbon, water, nitrogen, phosphorus, and sulfur.

9-12.EVS.1.2

Entropy and Spontaneous Change

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