Page 26 - Color Atlas of Biochemistry

Physical Chemistry 17

A. Forms of work

Higher Elevated position Voltage Educts
source

Potential Height Weight Voltage Charge Quantity

Lower position Change in free energy (∆G) Products
Ground
Lower

1. Mechanical work 2. Electrical work 3. Chemical work

2
-2
J = Joule = N · m =1 kg · m · s , 1 cal = 4.187 J

Form of work Intensity factor Unit Capacity factor Unit Work = · Unit

Mechanical Height m Weight J · m -1 Height · Weight J

V =
Electrical Voltage -1 Charge C Voltage · Charge J
J · C
Free-enthalpy
Chemical J · mol -1 Quantity mol ∆G · Quantity J
change ∆G

B. Energetics and the course of processes

∆P < 0 ∆P = 0 ∆P > 0 ∆P eff < 0

Process occurs Process cannot Coupled processes can
spontaneously occur occur spontaneously

Potential Potential
P 3 P 3

∆P M 1 ∆P 1 M 2

P 1 P 1
∆P
∆ P eff ∆P 2

P 2 P 2

1. Exergonic 2. Equilibrium 3. Endergonic 4. Energetically coupled

Koolman, Color Atlas of Biochemistry, 2nd edition © 2005 Thieme
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