Thermo Lecture 8 Flashcards
What characterizes a real, non-ideal solution?
Vmixing is not 0, Hmixing is not zero
Formula for activity?
αi = γixi
Activity of i = activity coeff’ of i x mole fraction of i
What is the equation for fugacity?
As P approaches zero, the fugacity divided by the partial pressure approaches 1. A.k.a as P decreases we approach ideal behaviour
What is the equation for Activity for gases?
αi = fi/foi (the availability of 'i' for a reaction) fi = fugacity of i foi = Standard state fugacity
What does activity ‘measure’?
A measure of the chemical potential of a component in a solution relative to the chemical potential of the same component in a stated given standard state
/the availability of a component for a reaction
How to you use a graph to determine chemical potentials at a given composition?
Graph of G against x, draw tangent to the curved line.
What do ‘excess functions’ do?
Account for the deviation from ideal solution behaviour
Formula for G of an ideal solution?
Gideal = Σμixi + RTΣxi ln(xi) *ai = xi for ideal solutions
Equation of Gexcess ?
Gexcess = RTΣχilnγi (dG_mixing - dG_ideal mixing)
Formula of Greal?
Gideal + Gexcess
What is the equilibrium constant (K)?
Describes the position of equilibrium in a chemical reaction?
What is the equation for K
K = Π(αi^νi) a = acitivity ν = stoichiometric coefficient, negative for reactants
What is the equation that relative G to K?
ΔG = -RTln(K)
as μi(pure) = Gi(pure)
What is ‘Affinity’ (A)?
the difference between chemical potentials of reactants and products/ distance from eq_m
How do we define the ‘extent of the reaction’ (ξ)?
pronounced ‘sigh’(???)
dξ = dn_i/v_i
change in number of moles/standard stoichiometric coefficient
