predicting pharmaceutical stability Flashcards
what is thermodynamics
general description of energy and its transfer
what does thermodynamics allow us to predict
whether a reaction will occur or not and what physical instabilities will occur like polymorphism and phase changes
in short, explain what each law of thermodynamics is
zeroth- concept of temperature
first- conservation of energy
second- entropy principle
third- absolute zero temperature
what has energy
any mass in any form of motion has energy
what is energy measured in
joules
what is an open system
both matter and energy can cross the boundary between system and its surroundings
what is a closed system
no matter can transfer through
what is an isolated system
no matter or energy transfer
what is a system
part of universe chosen in consideration
what is zeroth law
if A and B are in thermal equilibrium and so are B and C, then TA=TC
what is work
transfer of energy from one system to another by a force moving its point of application in its own direction
what symbol represents work
w
what is the change in energy in work associated with
ordered or coordinated movement of particles in 1 or more directions in the surrounding
what symbol represents heat
q
what is heat
transfer of energy due to differences in temperature
-involves trans/rotational motion and inter/intramolecular vibrations
what is the exchange in energy from heat associated with
disorder/chaotic movements of atoms
example of heat
ice melting
example of work
movement of piston due to expansion/compression of a gas
what is heat and work
energy in the process of being transferred
what does +ve and -ve heat mean
+ve=energy absorbed
-ve=energy given out
what does +ve and -ve work mean
+ve=work done on system, compression
-ve=work done by system, expansion
what is internal energy (u)
total energy in system
what is first law of thermodynamics
theres a change in internal energy when a system changes from an initial state with Ui to a final state with Uf
∆U=Uf-Ui
equation for first law of thermodynamics
∆U=q+w
equation for the enthalpy of an open system
∆H=∆U+P∆V
what is thermochemistry
study of heat changes with chemical reactions
what are the standard conditions
pure unmixed substance, 25 degrees celcius, 1 atm
what is standard enthalpy/∆H
enthalpy change when reactants in their standard states are converted into products in their standard states
what is hess’s law
enthalpy change is independent o the route taken
what is entropy
disorder of a system
(liquid to solid=more order=less entropy)
what is second law of thermodynamics
in isolated systems entropy increases by a spontaneous process
equation in second law of thermodynamics
∆S=q/T
are spontaneous processes reversible and what happens to the entropy
spontaneous processes are irreversible, entropy increases
reversible processes are in equilibrium and entropy remains unchanged
what is q(surr)
heat transferred to surroundings
∆S(surr) is proportional to ∆q(surr)
heat has more impact when transferred to a cold reservoir, what is the equation that shows this
∆S(surr) is proportional to 1/T(surr)
what is the third law of thermodynamics
entropy of a perfectly crystalline material is zero at T=0k
-at )k thermal motion is eliminated and there is no disorder
what are the causes of spontaneous change
- energy difference between initial and final states
- entropy difference between initial and final states
gibbs free energy equation
∆G=∆H-T∆S
what do values of ∆G mean
∆G<0 spontaneous
∆G=0 equilibrium
∆G>0 not spontaneous
what is ∆G in terms of work done
maximum non expansion work done at a constant pressure
describe the graphs of ∆G
∆G decreases= reaction goes to completion
∆G decreases then increases= equilibrium
∆G increases= reaction doesnt occur
equilibrium constant equation
Keq=[products]/[reactants]
what do the values of the equilibrium constant (K) mean
K»1 products dominate the reaction mixture
K«1 reactants dominant
K=1 reactants and products and in similar abundance
equation with ∆G and equilibrium constant
∆G=-RTlnK
