Lecture 1. Thermodynamics and Spontaneity Flashcards
What is the first law of thermodynamics ?
Energy cannot be created or destroyed only converted from one form to another. Energy is conserved
What is the equation for the first law of thermodynamics ?
dU = dq + dW Energy = Heat Transfer + Work Done
What information is the first law of thermodynamics missing ?
The spontaneity of physical and chemical transformations
What happens when a change occurs in an isolated system ?
The total energy of an isolated system remains constant but is parceled out in different ways
What is the direction of a change in an isolated system related to ?
The distribution of energy
What are spontaneous changes always accompanied by ?
A dispersal of energy or matter
What is a spontaneous process ?
A process which occurs without outside intervention
What direction do spontaneous processes occur in ?
One direction only
What is a non-spontaneous process ?
Requires energy to drive it forward
Is a spontaneous process energy dependent ?
No
What does thermodynamics tell us about and omit ?
The direction in which a process will occur but can say nothing about the speed or rate of the process
What speed may a spontaneous process be ?
Fast or slow
What is a very slow spontaneous process ?
Oxidation of glucose
What is entropy ?
A measure of spontaneous dispersal of energy
What is entropy measured at ?
A specific temperature
What does the first law of thermodynamics use to identify permissible changes ?
U or Energy
What does the second law of thermodynamics use entropy or S to identify ?
Spontaneous changes among permissible changes
What does the second law of thermodynamics state ?
A spontaneous process is one that results in an increase in the entropy of the universe which corresponds to the energy being dispersed in the process
What is the equation for dS or entropy ?
dS = dqrev/ T Entropy = Heat/Temperature
What is the equation for the change in entropy ?
Delta S = Integral (Heat/Temperature)
What is the equation for the entropy of a universe (Second law of thermodynamics)
Delta S total = Delta S sys + Delta S surr > 0
What are biological systems inherently organised and tend towards ?
A state of stability
What is gibbs energy ?
The energy that is truly free to do work
What is the equation of the change in gibbs energy ?
Delta G = Delta H - T(delta S)
What is another definition for gibbs energy ?
The energy available having adjusted for the entropy changes of the surroundings
How can a reduction in the change of entropy be rationalized ?
- The reaction goes from the higher-entropy gas molecule to lower-entropy liquid
- The reaction reduces the relative number of species present
What must gibbs energy be for a reaction to be spontaneous at constant temperature and pressure ?
Less than zero
Products must have a lower what than reactants ?
Gibbs energy
What happens when the gibbs energy is less than zero ?
Energy is transferred from the system to surroundings
What is the reaction called when gibbs energy is less than zero ?
Exergonic
What is reaction called when gibbs energy is greater than zero ?
Endergonic
What type of reaction is photosynthesis ?
Endergonic
Is photosynthesis a spontaneous reaction ?
No - it requires energy
What are the two groups of metabolic reactions ?
- Catabolic Reactions
2. Anabolic Reactions
What is a catabolic reaction ?
Exergonic (spontaneous) reactions that break down high energy compounds into simpler molecules
What is an anabolic reaction ?
Build up more complicated molecules from simpler subunits. Most of these reactions are endergonic
