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

Serbest enerji değişimi veya ΔG, belirli bir reaksiyonun standart serbest enerjisinin toplamı ve RT çarpı ürünlerin konsantrasyonlarının reaktanlara oranının doğal kütüğüdür.
Eğer ΔG bir reaksiyon negatifse, reaksiyon ileri doğru ilerler. ΔG, reaktanların konsantrasyonları azaldıkça ve ürünlerin konsantrasyonları arttıkça daha az negatif hale gelir.
Sonunda, ΔG, reaksiyon dengeye ulaştığında sıfıra eşittir, burada ileri ve geri reaksiyon hızları eşittir.
Dengede, ürünlerin ve reaktanların konsantrasyonunun oranı, denge sabiti K'ye eşittir.
Denklem, ΔG0 ve K.

serbest enerji ve denge

Free Energy and Equilibrium

Bir süreç için serbest enerji değişimi, itici gücünün bir ölçüsü olarak görülebilir. ΔG için negatif bir değer, süreç için ileri yönde bir itici gücü temsil ederken, pozitif bir değer, süreç için ters yönde bir itici gücü temsil eder. ΔG sıfır olduğunda ileri ve geri itici kuvvetler eşittir ve süreç her iki yönde de aynı oranda gerçekleşir (sistem dengededir). 

 Reaksiyon bölümü Q, bir denge sisteminin durumunun uygun bir ölçüsüdür. Q, sistem için kütle eylemi ifadesinin sayısal değeridir ve dengeye ulaşmak için reaksiyonun ilerleyeceği yönü belirlemek için kullanılabilir. Q, denge sabiti K'dan küçük olduğunda, dengeye ulaşılana ve Q = K'ye ulaşılıncaya kadar reaksiyon ileri yönde ilerleyecektir. Tersine, eğer Q > K ise, denge sağlanana kadar süreç ters yönde ilerleyecektir. 

 Standart olmayan koşullar altında (1 bar dışındaki basınçlar; 1 M dışındaki konsantrasyonlar) mevcut olan reaktanlar ve ürünlerle gerçekleşen bir sürecin serbest enerji değişimi, bu denkleme göre standart serbest enerji değişimiyle ilişkilidir: 

 ΔG = ΔG° + RT lnQ 

 R, gaz sabitidir (8,314 J/K mol), T, kelvin veya mutlak sıcaklıktır ve Q, reaksiyon bölümüdür. Gaz fazı dengesi için basınca dayalı reaksiyon bölümü QP kullanılır. Konsantrasyona dayalı reaksiyon bölümü QC, yoğunlaştırılmış faz dengesi için kullanılır. 

 Dengedeki bir sistem için Q = K ve ΔG = 0 olup önceki denklem şu şekilde yazılabilir: 

 0 = ΔG° + RT lnK (dengede) 

 ΔG° = −RT lnK 

 Denklemin bu formu, iki temel termodinamik özellik arasında faydalı bir bağlantı sağlar ve denge sabitlerini standart serbest enerji değişikliklerinden türetmek için kullanılabilir veya tam tersi şeklinde.

 Bu metin Openstax, Kimya 2e, <a href="https://openstax.org/books/chemistry-2e/pages/16-4-free-energy">Bölüm 16.4: </a><a href="https://openstax.org/books/chemistry-2e/pages/16-4-free-energyy">Serbest Enerji</a>'dan uyarlanmıştır.

Serbest Enerji ve Denge

Bir süreç için serbest enerji değişimi, itici gücünün bir ölçüsü olarak görülebilir. ΔG için negatif bir değer, için itici bir gücü temsil eder ...

Education

JoVE Core

Cell Biology

Hücre Biyolojisi

Unit 1

Ünite 1

Energy and Catalysis

Enerji ve Kataliz

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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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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 Hücre Biyolojisi, anlaşılması kolay ancak kapsamlı animasyonlu video derslerde karmaşık hücresel süreçleri gösterir. Bu koleksiyon, organeller ve zarlar, hücresel taşıma ve hücre enerjileri dahil olmak üzere hücrelerin temel bileşenlerine ve işlevlerine odaklanır. Gerçek dünya araştırma deneylerinde hücre biyolojisinin uygulanmasını gösteren bilim insanı eylem videoları ile tamamlanmaktadır.

Free Energy and Reaction Direction

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