Trends in Gibbs Free Energies of Formation Heat Capacities Enthalpies of Vaporization and Viscosities vs Strait Alkane Length Table 1 Thermodynamic and fluid properties vs length of straight alkane length1 2 3 4 Alkane Δ_f G at 298 K kJ mol ΔH_vap at Boiling Point kJ mol C_p at 298 K J mol K µ at 298 K µPa s Methane 50 8 8 6 37 39 10 3 Ethane 32 9 15 7 52 49 11 Propane 23 4 19 5 73 60 7 4 Butane 15 6 23 4 98 49 7 Pentane 9 2 26 7 120 1 11 7 Hexane 4 2 31 5 196 5 6 5 Heptane 1 3 32 224 7 6 5 Octane 6 4 36 3 255 6 7 5 The table above was constructed at first through the use of Google Finding reliable data tended to be easier the smaller the alkane was Usually the source used for one property of methane always had the next five alkanes as well Searches about octane viscosity for example either did not have a reliable source or cost a hefty fee to look at Most of heptane s and octane s values came from Knovel Knovel always gives reliable verified information which ended up saving a lot of time One source that was particularly astounding to me was a 332 page paper written by James S Chickos and William E Acree Jr1 It contains tabulated data for thousands of molecules enthalpies of vaporizations over many temperature ranges The references alone are over three pages as well Figure 1 Alkane length vs Gibbs Free Energies of Formation 2
