U1- Topic 3: Thermodynamics Flashcards
System
Anything of interest to a biologist
Surroundings
Everything OUTSIDE of the system
Open System
Matter and Energy can cross boundaries
Closed System
Energy can cross boundaries but matter cannot
Isolated System
Matter and Energy CANNOT cross boundaries
Energy = ? Work = ?
Energy is the ability to cause change
Work is the change that requires energy
Potential Energy
“Energy at rest”
stored energy due to position of an object
examples: electrons in chemical bond
Kinetic Energy
“Energy doing work”
the energy of motion/change
example: heat, muscle contraction
First Law of Thermodynamics
Energy is neither created nor destroyed
Enthalpy
(HEAT, ΔH)
SUM of all the potential energy plus all the kinetic energy of all the matter in the system.
Exothermic Reaction
Enthalpy is decreasing.
Heat is released by the system to the surroundings.
Change in enthalpy is NEGATIVE.
Enthalpy of products is LESS than enthalpy of the reactants.
Endothermic Reaction
Enthalpy is increasing.
Heat is absorbed by the system from the surroundings.
Change in enthalpy is POSITIVE.
Enthalpy of products is MORE than enthalpy of the reactants.
Definition of Spontaneous Reaction
Reaction CAN occur in forward direction under current conditions.
- Energetically favourable
- NOT instantaneous
Definition of Non-Spontaneous Reaction
CANNOT occur in forward direction under current conditions.
- Stays equilibrium or goes backwards
Entropy
Measure of dispersion of energy in the system.
Amount of disorder/ randomness.
Positive ΔS
Energy has been DISPERSED in the system
Reactants have more energy
Negative ΔS
Energy has been CONCENTRATED in the system.
Second Law of Thermodynamics
Any spontaneous process increases the disorder or randomness in the universe.
Results in an INCREASED in the TOTAL entropy of the universe.
Total Entropy
ΔS(total) takes into account the system and the surroundings, total of universe
Entropy Formula
ΔS total = ΔS system + ΔS surroundings
Free Energy (G)
measure of energy in a system that is free/ available to do work.
- reactants have more free energy than products
ΔG = negative, spontaneous
If energy is not available to change the system….ΔG
ΔG = positive, increase in free energy
Exergonic
ΔG < 0 (NEGATIVE)
Free energy is decreasing in the system
- free energy exiting system
SPONTANEOUS
Endergonic
ΔG > 0 (POSITIVE)
Free energy is increasing in the system
- free energy entering system
NON-SPONTANEOUS
Catabolism
Breaking down of complex molecules
Anabolism
Building up of complex molecules
“Connected” Reactions
Product of the first reaction is the substrate/reactant for the second reaction
Short-Term Potential Energy Storage Molecule
ATP
- stores P.E by holding 3 negative charges close together
- like charges REPEL, covalent bonds hold P.E
“Coupled” Reactions
Single reaction with 2 things happening, occurring at the same place at the same time.
