Topic 2: Thermodynamics Flashcards
Example of an isolated system
The universe
Closed system?
Allows energy but not matter to pass through
Open system?
Allows energy and matter to pass through
Relative Ep of molecules with non-polar covalent bonds
Higher Ep in general
Examples of non-polar covalent bonds?
C-C, C-H, C8H18 (gasoline)
An important source of cellular energy
Electrochemical Gradient
First law of thermodynamics?
energy cannot be created or destroyed
Enthalpy (3 points)
The sum of all potential and kinetic energy present in a system
Can be positive or negative, depending on reaction
Changes when work occurs
Entropy (3 points)
How dispelled energy is in the universe
Can be positive or negative, depending on reaction
Must always increase
When ΔS>0…
energy has become more dispered
When ΔS<0…
Energy has become less dispered
Second law of thermodynamics
the total entropy of the universe must always increase
What determines the spontaneity of a reaction?
Entropy! ΔS must be larger than 0
Two types of entropy?
Why are they important?
Entropy of system, and entropy of surroundings
Even if the entropy of the system decreases, as long as the entropy of the surroundings increases to a greater degree, reaction is spontaneous. ΔS>0
Describe Free Energy (G)
Molecules have free energy, meaning the ‘extra’ energy in a system that is free to do work
When ΔG>0….
energy is not available for work to occur
When ΔG<0…
energy is available for work to occur
Exergonic means…
a reaction will happen (spontaneous)
For the reaction to be exergonic and spontaneous…
ΔS>0 and ΔG<0
What units does ΔG use?
kJ/mol
What units does ΔS use?
J/mol
When will ΔG=0?
When chemical equilibrium is reached
The sum of all reactions in a cell:
metabolism
The breaking down of complex molecules:
Catabolism
