This paper uses self-association model to compute the concentration dependence of free energy of mixing (Ã?°Ã?Ã?Ã?ºÃ?°Ã?Ã?â??Ã?â?¬), activity (a), and the microscopic properties such as concentration fluctuation in the long wavelength limit (Ã?°Ã?Ã?â??Ã?â? Ã?°Ã?Ã?â??Ã?Ã?°Ã?Ã?â??Ã?), and Warren-Cowley short range order parameter (Ã?°Ã?Ã?â?ºÃ?¼1) for Sn-Zn binary liquid alloy. The calculation reveals the homo-coordination or phase separation at all concentrations with moderate interaction for Sn-Zn liquid alloy at 750 K.