L5 & L6: Thermodynamics Flashcards
What is thermodynamics?
The science of energy transfer
- whether ac reaction or process will take place (not how fast)
What is energy?
The ability to perform work
What is kinetics?
The study of rates associated with a reaction or process
What is kinetic energy?
The energy of moving objects or mass
What is potential energy?
Energy that is stored
What is heat?
- Energy caused by molecular motion
- thermal energy transfer between objects
What is temperature?
The propensity for heat to flow from one body to another
What is the equation for fahrenheit to celsius?
C = (F - 32) / 1.8
What is work? and what is it determined by?
The transfer of energy in an ordered fashion
- defined by energy barrier it overcomes
(J)
What is U, W and Q?
U - total internal energy of system
W - work
Q - heat
What type of systems are there?
- isolated
- closed
- open
What is an isolated system?
There is no exchange in matter and energy
What is a closed system?
No wxchange in matter, but there is exchange in energy
What is an open system?
There is exchange in matter and energy
What are the signs for work done?
+W: work done ON system
-W: work donw BY system
What are the signs for heat?
+Q: Heat ADDED TO system
-Q: Heat REJECTED BY system
What is the 1st law of thermodynamics?
Algebraic sum of all energy changes in an isolated system is zero
= energy cannot be created or destryoes but merely trasnferred
What are the 7 main forms of energy?
- electrical
- gravitational
- chemical
- radiation
- thermal
- mechanical
- nuclear
What is enthalpy?
The heat energy change within a system is expressed as enthalpy
- expressed as a change value
What are the signs for enthalpy?
+ve : endothermic = broken bonds = energy absorbed from the surroundings
-ve : exothermic = bond made = energy lost to the surroundings
What are the 3 main types of enthalpy
Hc : crystallisation, liquid state to the solid state
Hf : melting, f stands for fusion
Hv: evaporation of a volatile solvent, v stands for vaporisation
What is the 2nd law of thermodynamics?
The entropy of an isolated systen will either increase or stay the same but may not decrease
What is entropy?
A measure of disorder (and probability)
When does entropy increase?
Entropy increases when disorder increases
What are the two ways of looking at entropy?
- probability
- molecular motion
How does probability affect entropy?
The more random/disordered an event is, the more likely it is to occur
How does molecular motion affect entropy?
The greater the range of the possible motions (degrees of freedom), the greater the entropy
- these motions are almost always present and increase with increased temperature
What is heat capacity?
Amount of heat to be supplied to an object to produce a unit charge in its temperature
(J/K)
Reflect the ability to store heat energy
What material have a higher heat capacity and why?
- material with a higher range of molecular mobilities (degrees of freedom) can store more energy
= have a higher entropy
What is the 3rd law of thermodynamics?
At absolute zero, the entropy of a perfectly crystalline substance is zero
= perfectly ordered
Will a reaction take place spontaneously?
Lies in the balance between the enthalpy and entropy?
What is the GFE equation?
Delta G = Delta H - T delta S
G - gibbs free energy
H - enthalpy
T - temperature
S - entropy
What is GFE?
Gibbs free energy
The energy availability to perform work
What are the signs for GFE?
+ve : system can perform work on the surroundings and the reaction will be spontaneous
-ve: system is not able to perform work on its surroundings and the reaction will not be spontaneous
What is a spontaneous reaction is favoured by?
- -ve delta H (heat given out)
- +ve delta S (system becoming more disordered)
What are the main parameters in the drug discovery process?
- solubility
- melting point
- partitioning
What is solubility?
The max eq conc og a drig in a given solvent (saturation)
What is melting point?
The transition from the crystalline to the liquid state (indicative of the bond strength)
What is partitioning?
The distribution of a drug between oil and aq phases (indicative of permeation across biological membranes)
How does thermodynamics help in drug receptor interactions?
Provides insights into
- bond strengths
- free energy of interactions
- molecular modelling
- longevity of drug-receptor interactions
