8. Thermodynamics Flashcards
What is thermodynamics concerned with?
The interconversions of different forms of energy
Provides a means for deciding whether or not a process will happen spontaneously BUT does not tell you how fast it will occur
What are the two different categories which energy can be divided into?
What is the basic unit of energy?
Kinetic energy: Includes all forms of energy that result from MOVEMENT e.g. heat (molecular motion) and electrical energy and mechanical energy
Potential energy: All forms of energy that are STORED e.g. in chemical bonds, concentration gradients , electrical potential (separation of charges) and in nuclei of atoms
Basic unit of energy: Joule (J)
What is the first law of thermodynamics?
What is the internal energy of a system denoted by when the system is at constant pressure?
States that energy is CONSERVED (either within an isolated system or between a system and its surroundings) when processes occur
Determine the conditions under which specific processes can or cannot take place
Change in internal energy = Difference between the energy gained and the energy lost= Energy conservation
Denoted by: H (enthalpy)
What is entropy (S)?
What are the units for entropy?
Measure of the disorder or randomness in a system
The higher the entropy, the more disordered and random the system
Units: Energy/ Temperature ( J K^-1)
K= °C + 273.15
What is the second law of thermodynamics?
States that entropy always INCREASES when processes occur
Biological systems will always become more DISORDERED= entropy increases
What is the difference between system and its surroundings?
What happens to the entropy inside a living organism as it grows and develops?
System: Matter within a defined region of space
Surroundings: Matter in the rest of the universe
Entropy in living organisms DECREASES= become more ordered
Entropy may be locally decreased in formation of ordered structures ONLY if entropy in other parts of the universe (surroundings) is increased by an equal or greater amount e.g. releasing heat to its surroundings
Overall= Entropy of organism + Surroundings = INCREASES
How is entropy related to temperature?
Amount of entropy in a system increases as the temperature increases
What does Gibbs Free Energy do?
What is the equation?
What is the units?
Combines energy (H) and entropy (S) to give an overall measure which determines whether a process will occur
ΔG = ΔH−TΔS
Normally expresses as the basis of change in free energy per mole of reactant converted to product: kJ mol^-1
What has to happen to Gibbs Free Energy for a process to occur spontaneously?
What happens when ΔG= 0?
ΔG must be negative as it is only negative when entropy increases
When ΔG =0, the system is at equilibrium
What does ΔG°’ mean?
The standard free energy change for conversion of 1 mole of reactant(s) to 1 mole of product(s) under conditions where concentrations of all components except water are held constant at 1M, and T= 25°C and pH= 7
