Any function can be expanded in a Taylor series, around a base point

is the base value of , at which the function is expanded

Consider the van der Waals equation of state for real gases, for a constant number of moles,

Where:

number of moles

pressure

temperature

universal gas constant

, particular gas constants

Perform linearization for

Express the result in terms of deviance variables

f[x1(t),x2(t)]=f(x1,x2)+x1fx~1,x2[x1(t)x1]+x2fx1,x2[x2(t)x2] (P+V2n2a)(Vnb)=nRuT T=f(P,V)