Modification of van der Waals family equations of state

The main aim of this paper is to identify some simple and accurate van der Waals family equations of state. In this respect, two modified van der Waals-type EOSs have been investigated and applied to correlate PVT properties of several molecular fluids as well as ionic liquids. The outcomes of computations have been compared with literature data and with the original van der Waals-type EOSs. The results show that addition of a variable exponent in the power of the temperature in the attractive term of equations of state and taking it as a function of acentric factor will improve the van der Waals equations of state.