1、先求出沸点升高常数kb,已知质量摩尔浓度:m = [0.605 / M(C6H6)] *1000 /40 = (0.605*1000 / 78 ) / 40 = 0.1939 (mol / kg-1溶剂)△t = kb *m 0.50 = kb * 0.1939kb = 2.57862、求未知物的摩尔质量M0.42 = 2.5786 * (0.450*1000 / M ) / 40M = 69