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

الانتروبيا ، التي يتم اختصارها باسم S ، هي المقياس الديناميكي الحراري للاضطراب أو العشوائية. الأنظمة ذات الاضطراب الأكبر لديها إنتروبيا أعلى من تلك التي تعاني من اضطراب أقل.
على سبيل المثال ، تتمتع سلسلة الأحماض الأمينية غير المطوية بإنتروبيا أعلى مما كانت عليه عندما تكون السلسلة مطوية بشكل صحيح لأن السلسلة الخطية تكون أكثر مرونة وغير منظمة من البروتين المعبأ بإحكام.
ينص القانون الثاني للديناميكا الحرارية على أن إنتروبيا النظام المعزول تزداد دائما. هذا يعني أن كل شيء يصبح أكثر اضطرابا بدون مدخلات خارجية.
نادرا ما تحدث الأنظمة المعزولة بشكل طبيعي ، لذلك غالبا ما تفحص الديناميكا الحرارية التغيير في إنتروبيا الكون بأسره. يشمل التغيير في إنتروبيا الكون كلا من التغيرات الانتروبية للنظام الذي تتم دراسته ومحيطه.
تحدث تلقائيا عملية تزداد فيها إنتروبيا الكون ، أي العملية التي تحتوي على ΔS أكبر من الصفر ، تلقائيا. العملية التي تنخفض فيها الانتروبيا أو لها −ΔS ليست عفوية وتحتاج إلى مدخلات الطاقة لتحدث.

القانون الثاني للديناميكا الحرارية

<div style="direction: rtl;">
أثناء السعي لتحديد خاصية يمكنها التنبؤ بشكل موثوق بمدى عفوية حصول حدث ما، توصل الباحثون إلى مرشح واعد إلى حد كبير: إنه الإنتروبيا أو القصور الحراري. يشير العلماء إلى مقياس العشوائية أو الاضطراب داخل نظام ما بالإنتروبيا. فوجود حالة من الإنتروبيا العالية يعني اضطرابًا عاليًا وطاقة منخفضة. لفهم هذه الظاهرة بشكل أفضل، سنأخذ مثال غرفة نوم لطالب جامعي. إذا لم يتم بذل أي طاقة لترتيبها، فسوف تصبح الغرفة فوضوية بسرعة. و ستكون في حالة شديدة الفوضى، ذات إنتروبيا عالية. يجب إذن استثمار الطاقة فيها على شكل قيام الطالب بمجهود لترتيبها من الفوضى مثلا، من أجل إعادتها إلى حالة النظافة والنظام. فتصير آنذاك مثالا على الانتروبيا المنخفضة.

العمليات التي تنطوي على زيادة في إنتروبيا النظام (ΔS > 0) غالبًا ما تكون عفوية؛ ومع ذلك، فإن الأمثلة على عكس ذلك كثيرة. ومن خلال توسيع النظر في تغيرات الإنتروبيا لتشمل المناطق المحيطة، قد نتوصل إلى نتيجة مهمة فيما يتعلق بالعلاقة بين هذه الخاصية والعفوية. في النماذج الديناميكية الحرارية، يشتمل النظام والبيئة المحيطة المحيطة على كل شيء، أي الكون، وبالتالي فإن ما يلي صحيح:

ΔS_univ = ΔS_sys + ΔS_surr

ينص القانون الثاني للديناميكا الحرارية على أن جميع التغيرات التلقائية تسبب زيادة في إنتروبيا الكون. ويرد في الجدول 1 ملخصا للعلاقة بين الإنتروبيا وعفوية حصول حدث ما.

الجدول 1: العلاقة بين الإنتروبيا وعفوية حصول الحدث.

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<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>ΔSuniv > 0</td>
			<td>عفوي</td>
		</tr>
		<tr>
			<td>ΔSuniv < 0</td>
			<td>غير عفوي، تلقائي في الاتجاه المعاكس</td>
		</tr>
		<tr>
			<td>ΔSuniv = 0</td>
			<td>عند التوازن</td>
		</tr>
	</tbody>
</table>
</div>
</div>

في السعي لتحديد خاصية قد تتنبأ بشكل موثوق بعفوية العملية ، تم تحديد مرشح واعد: الانتروبيا. علماء...

Education

JoVE Core

Cell Biology

بيولوجيا الخلية

Unit 1

الوحدة الأولى

Energy and Catalysis

الطاقة والتحفيز

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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...

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entropy within the cell

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Gibbs Free Energy and Reaction Work

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endergonic and exergonic reactions in the cell

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

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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

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

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How Enzymes Lower Reaction Energy

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Graphing Enzyme Kinetics Data

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turnover number and catalytic efficiency

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

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cooperative allosteric transitions

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ribozymes

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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.

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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.

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The Water Cycle

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The Phosphorus Cycle

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The Sulfur Cycle

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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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