- #1
hosein
Integral constant for internal energy of ionic liquid
I have a question, and I will be really grateful if someone helps me. I have a polynomial equation for internal energy which I calculated by integration an equation of state formula, which is based on density. But, because I calculated this using integration one integration constant which is temperature dependent( based on other articles) that I don't know how can I formulate it to have its magnitude to calculate internal energy at other range of data. My simulation box has contained 200 molecules of ionic liquid with one negative ion( PF6) and a positive one( butyl methyl imidazolium). Because according to internal energy equation at zero density internal energy is equal to the integration constant, we considered it as ionic liquid internal energy at ideal gas state. With all those in mind, how can I use a degree of freedom of rotational, vibrational, and translational to formulate this integration constant dependent of temperature to use it in other range of data? Or, is there any other method to formulate it?
the main equation is this:
([Zth + Zin] - 1)V^2 = e +f/rho+ g*rho^2
in=internal
th=thermal
Z=compressibility factor
(Zth - 1)V^2 = eth +fth/rho+ gth*rho^2
(Zin)V^2 = ein +fin/rho+ gin*rho^2
Ein =∫Pin/rho^2 drho+ F(T) = RT[(ein(T)/2)*rho^2+ fin(T)*rho + (gin(T)/4)*rho^4]+ F(T)
F(T)?
the main equation can be fitted to experimental data, but the Ein cannot.
Actually, I considered the assumption of zero density(ideal gas state for my ionic liquid), but it will show that Ein=F(T), somehow it will help that maybe F(T) can be Ein at the ideal gas state, and if I wanted to formulate it with degree of freedom it will be 3RT( polyatomic ideal gas).
But I calculated Cv and Cp from Ein and when I fitted them( Cv and Cp) to experimental data, their constant(F'(T) or their ideal part contribution which is the derivation of Ein F(T)) shows temperature dependency which means F(T) should have a power 2 or more temperature in its formula to produce a derivation which has temperature dependency.
Actually, the only thing that I can guess is that F(T) could be formulated properly if I calculate the degree of freedom classically for my ionic liquid ([BMIM][PF6]), which I don't know how.
thanks in advance
I have a question, and I will be really grateful if someone helps me. I have a polynomial equation for internal energy which I calculated by integration an equation of state formula, which is based on density. But, because I calculated this using integration one integration constant which is temperature dependent( based on other articles) that I don't know how can I formulate it to have its magnitude to calculate internal energy at other range of data. My simulation box has contained 200 molecules of ionic liquid with one negative ion( PF6) and a positive one( butyl methyl imidazolium). Because according to internal energy equation at zero density internal energy is equal to the integration constant, we considered it as ionic liquid internal energy at ideal gas state. With all those in mind, how can I use a degree of freedom of rotational, vibrational, and translational to formulate this integration constant dependent of temperature to use it in other range of data? Or, is there any other method to formulate it?
the main equation is this:
([Zth + Zin] - 1)V^2 = e +f/rho+ g*rho^2
in=internal
th=thermal
Z=compressibility factor
(Zth - 1)V^2 = eth +fth/rho+ gth*rho^2
(Zin)V^2 = ein +fin/rho+ gin*rho^2
Ein =∫Pin/rho^2 drho+ F(T) = RT[(ein(T)/2)*rho^2+ fin(T)*rho + (gin(T)/4)*rho^4]+ F(T)
F(T)?
the main equation can be fitted to experimental data, but the Ein cannot.
Actually, I considered the assumption of zero density(ideal gas state for my ionic liquid), but it will show that Ein=F(T), somehow it will help that maybe F(T) can be Ein at the ideal gas state, and if I wanted to formulate it with degree of freedom it will be 3RT( polyatomic ideal gas).
But I calculated Cv and Cp from Ein and when I fitted them( Cv and Cp) to experimental data, their constant(F'(T) or their ideal part contribution which is the derivation of Ein F(T)) shows temperature dependency which means F(T) should have a power 2 or more temperature in its formula to produce a derivation which has temperature dependency.
Actually, the only thing that I can guess is that F(T) could be formulated properly if I calculate the degree of freedom classically for my ionic liquid ([BMIM][PF6]), which I don't know how.
thanks in advance