Lecture 2 Thermodynamics Flashcards
Define thermodynamics
A set of principles that apply to all physical and biological processes and govern the conditions under which they can occur
What are the 3 laws of thermodynamics?
1st- energy can neither be created nor destroyed only interconverted between forms
2nd- Level of disorder in a system and its surroundings always increases
3rd - Entropy approaches a constant value when temp is 0
Define system
Whatever part of the universe we are interested in
Define closed system
Cannot exchange matter across boundaries but some energy
Define open system
Matter and energy back and forth across boundaries
Define surroundings
Everything that surrounds the system
Define enthalpy (H)
Heat storage capacity of a system
What is the equation of enthalpy?
H = E + (P x V)
Enthalpy (J) = internal energy (J)+ (pressure (Pa) x volume (m3))
How is the change in enthalpy and energy in liquids and solids similar?
There is little change in volume
Define exothermic
Release of heat in a reaction
Define endothermic
Heat is absorbed in a reaction
Define entropy
Levels of disorder in a system
High entropy = gas
Low entropy = solid
What is Gibbs Free Energy (G)?
The amount of available energy to do work
Gibbs free energy calculation
Change in G= Change in H - Tx change in entropy
G= change in gibbs free energy KJ/mol
H= change in enthalpy (J)
T= Temp (K)
S= Change in entropy (J/K)
How to convert from degrees to K?
Add 273
What is the standard biological conditions?
37 degrees 310K AND pH 7 so we use Change in G degrees sign ‘
Define exergonic
Excitable - releases energy
Define endergonic
Requires energy to initiate
What is activation energy?
Energy put into the system for a reaction to occur
What are the 5 rules of delta G
- Reactions occur spontaneously if change in G is less than 0
- Reactions cant occur if change in G is greater that 0
- At equilibrium G= 0
- Free energy of reactants and products not the path
- No info on rate
What is a coupled reaction?
A reaction that cant occur spontaneously so an energy input is required. Fundamental in metabolism
What is an anabolic reaction?
Constructing molecules from smaller units
What is a catabolic reaction?
Breaking down molecules to form smaller units
What is the most used activated carrier?
ATP
Hydrolysis has a change in G of -30.5 KJ/mol
