224mLO2是0.01mol,转移0.04mole。可知另一极是2M2+ +4e===2M,该金属摩尔质量为1.28÷(0.04÷2)=64所以金属M为Cu溶液中消耗了0.02molCu2+,由电荷守恒,必然生成0.04molH+。故H+浓度为0.04÷0.1=0.4mol/L