反应前后气体体积差△V = 1.2a - a = 0.2a L2O3 == 3O2 △V44.8 22.4 V 0.2a L44.8/V = 22.4/0.2a解得V = 0.4a L所以混合气体中O3体积 = 0.4a L,O2体积 = 0.6a LO3质量分数 = 4*48/(4*48+6*32) = 50%O2质量分数 = 1-50% = 50%