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

エントロピーは、Sと略され、無秩序またはランダム性の熱力学的尺度です。無秩序なシステムは、無秩序でないシステムよりもエントロピーが高くなります。
たとえば、折りたたまれていないアミノ酸鎖は、鎖が適切に折りたたまれている場合よりもエントロピーが高くなります。これは、線状鎖が密集したタンパク質よりも柔軟で組織化されていないためです。
熱力学の第二法則は、孤立したシステムのエントロピーは常に増加すると述べています。これは、外部からの入力がないと、すべてがより無秩序になることを意味します。
孤立したシステムが自然に発生することはめったにないため、熱力学はしばしば宇宙全体のエントロピーの変化を調べます。宇宙のエントロピーの変化には、研究対象のシステムとその周囲のエントロピーの変化の両方が含まれます。
宇宙のエントロピーが増加するプロセス、つまりΔSがゼロより大きいプロセスは、自然に発生します。エントロピーが減少する、または-ΔSを持つプロセスは自発的ではなく、エネルギー入力が発生する必要があります。

熱力学の第二法則

プロセスの自発性を確実に予測できる特性を見つける探求の中で、有望な候補が見つかりました。それはエントロピーです。 科学者は、システム内のランダム性または無秩序の尺度をエントロピーと呼んでいます。 エントロピーが高いということは、無秩序性が高く、エネルギーが低いことを意味します。 エントロピーをより深く理解するには、学生の寝室を思い浮かべてください。 エネルギーや労力を注がなければ、部屋はすぐに散らかってしまいます。 それは非常に無秩序な、高いエントロピーの状態で存在することになります。 部屋を清潔で秩序のある状態に戻すには、生徒が作業をして、すべてを片づけたりするという形で、システムにエネルギーを注ぎ込む必要があります。 この状態は低エントロピーの状態です。

システムのエントロピーの増加 (ΔS > 0) を伴うプロセスは、多くの場合自発的です。 しかし、その逆の例はたくさんあります。 エントロピー変化の考察を環境を含めて拡張することによって、この性質と自発性の関係について重要な結論に達する可能性があります。 熱力学モデルでは、システムと環境がすべて、つまり宇宙を構成するため、次のことが当てはまります。

ΔSuniv = ΔSsys + ΔSsurr

熱力学の第 2 法則は、すべての自発的変化が宇宙のエントロピーの増加を引き起こすと述べています。 プロセスのエントロピーと自発性の関係の概要を表 1 に示します。

表 1: エントロピーとプロセスの自発性の関係

<table style="border-collapse:collapse; border:1px solid #444; font-family: Arial, sans-serif; width:100%; max-width:560px;">
	<thead>
	</thead>
	<tbody>
		<tr>
			<td style="border:1px solid #444; padding:8px;">ΔSuniv > 0</td>
			<td style="border:1px solid #444; padding:8px;">自発的</td>
		</tr>
		<tr>
			<td style="border:1px solid #444; padding:8px;">ΔSuniv < 0</td>
			<td style="border:1px solid #444; padding:8px;">非自発的（逆方向の自発的）</td>
		</tr>
		<tr>
			<td style="border:1px solid #444; padding:8px;">ΔSuniv = 0</td>
			<td style="border:1px solid #444; padding:8px;">平衡状態</td>
		</tr>
	</tbody>
</table>

このテキストは Openstax, Biology 2e から引用したものです。<a href="https://openstax.org/books/biology-2e/pages/6-3-the-laws-of-thermodynamics">Section 6.3: The Laws of Thermodynamics</a> Openstax、化学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>

プロセスの自発性を確実に予測できる特性を特定するために、エントロピーという有望な候補が特定されました。科学 者。。。

Education

JoVE Core

Cell Biology

細胞生物学

Unit 1

ユニット1

Energy and Catalysis

エネルギーと触媒

KEY TERMS AND CONCEPTS

主要用語と概念

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

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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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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

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free energy and equilibrium

Free Energy and Reaction Direction

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non-equilibrium in the cell

Cells Stay Out of Equilibrium

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oxidation and reduction of organic molecules

oxidation-and-reduction-of-organic-molecules

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catalytically perfect enzymes

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introduction to mechanisms of enzyme catalysis

introduction-to-mechanisms-of-enzyme-catalysis

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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 細胞生物学は、複雑な細胞プロセスを、わかりやすく包括的なアニメーション ビデオ レッスンで説明します。このコレクションは、細胞小器官や膜、細胞輸送、細胞のエネルギー学など、細胞の必須コンポーネントと機能に焦点を当てています。これは、実際の研究実験における細胞生物学の応用を実証する科学者による実際のビデオによって補足されています。

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9-12.EVS.1.2

Entropy and Spontaneous Change

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