(a) describe the joule-thomson effect and explain its relationship enthalpy process. hence explain why the joule-thomson coefficient is given by: to a constant дт др h [6 marks] (b) the equation of state for one mole of a real gas with low density may be written in terms of the virial expansion: rt + b2(t)р pv where b2(t) depends only on temperature and differs from one gas to another. find an expression for the joule-thomson coefficient ajt for this gas, and discuss the circumstances in which the joule-thomson process can be used to cool the gas.