Name: free energy and reaction direction
Uploaded: 2023-04-30T10:09:12.000Z
Duration: 55 s
Channel: JoVE

자유 에너지 변화 또는 ΔG, 특정 반응의 표준 자유 에너지와 RT의 합에 반응물에 대한 생성물 농도 비율의 자연 로그를 곱한 값입니다.
ΔG 가 음수이면 반응이 앞으로 진행됩니다. ΔG는 반응물의 농도가 감소하고 생성물의 농도가 증가함에 따라 음수가 줄어듭니다.
결국 ΔG는 반응이 정방향 및 역방향 반응 속도가 동일한 평형에 도달하면 0과 같습니다.
평형에서 생성물과 반응물의 농도 비율은 평형 상수 K와 같습니다.
방정식을 재배열하여 ΔG0 및 K.

자유에너지와 평형

Free Energy and Equilibrium

프로세스의 자유 에너지 변화는 프로세스의 추진력을 측정하는 것으로 볼 수 있습니다. ΔG의 음수 값은 정방향 프로세스의 추진력을 나타내고, 양수 값은 역방향 프로세스의 추진력을 나타냅니다. ΔG가 0이면 정방향 및 역방향 구동력이 동일하고 프로세스가 양방향에서 동일한 속도로 발생합니다(시스템이 평형 상태에 있음).

반응지수 Q는 평형 시스템 상태를 측정하는 편리한 척도입니다. Q는 계의 질량작용식의 수치이며, 평형을 이루기 위해 반응이 진행되는 방향을 식별하는 데 사용할 수 있습니다. Q가 평형 상수 K보다 작으면 반응은 평형에 도달하고 Q = K가 될 때까지 정방향으로 진행됩니다. 반대로, Q > K이면 평형에 도달할 때까지 공정이 역방향으로 진행됩니다.

비표준 조건(1bar 이외의 압력, 1M 이외의 농도)에서 반응물 및 생성물이 존재하는 공정에 대한 자유 에너지 변화는 다음 방정식에 따른 표준 자유 에너지 변화와 관련됩니다.

ΔG = ΔG° + RT lnQ

R은 기체 상수(8.314 J/K mol), T는 켈빈 또는 절대 온도, Q는 반응 지수입니다. 기체상 평형의 경우 압력 기반 반응 지수 QP가 사용됩니다. 농도 기반 반응 지수 QC는 응축 상 평형을 위해 사용됩니다.

평형 상태의 시스템에 대해 Q = K 및 ΔG = 0이며 이전 방정식은 다음과 같이 쓸 수 있습니다:

0 = ΔG° + RT lnK(평형 상태)

ΔG° = -RT lnK

이러한 형태의 방정식은 두 가지 필수 열역학적 특성 사이의 유용한 연결을 제공하며 표준 자유 에너지 변화로부터 평형 상수를 유도하는 데 사용될 수 있으며 그 반대의 경우도 마찬가지입니다.

이 텍스트는 Openstax, Chemistry 2e에서 가져온 것입니다, <a href="https://openstax.org/books/chemistry-2e/pages/16-4-free-energy">Section 16.4: Free Energy.</a>

공정에 대한 자유 에너지 변화는 그 원동력의 척도로 볼 수 있습니다. ΔG에 대한 음수 값은 ...

Education

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JoVE Core

Cell Biology

세포생물학

Unit 1

제1단원

Energy and Catalysis

에너지 및 촉매

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 be used to predict which way a reaction will shift to reach equilibrium. If Q is less than the equilibrium constant, K, the reaction proceeds forward until Q = K. If Q is greater than K, the process shifts in reverse until equilibrium is reached.

For reactions under nonstandard conditions, ΔG depends on both the standard free energy change and the reaction quotient. The relationship is ΔG = ΔG° + RT ln Q, where R is the gas constant, T is temperature in kelvin, and Q is the reaction quotient. For gas-phase equilibria, the pressure-based quotient QP is used. For condensed-phase equilibria, the concentration-based quotient QC is used.

At equilibrium, Q = K and ΔG = 0. Substituting that condition into the equation gives 0 = ΔG° + RT ln K. This can be rearranged to ΔG° = −RT ln K. That link lets chemists find an equilibrium constant from a standard free energy change, or find a standard free energy change from K.

Free Energy and Reaction Direction

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free energy and equilibrium

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non-equilibrium in the cell

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key terms and concepts

Learn how free energy change, reaction quotient, and equilibrium constant work together to show reaction direction and equilibrium in chemistry.

Free Energy and Reaction Direction | 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.

Free Energy and Reaction Direction

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