不要文字说明.

两份双氧水生成一份氧气
2H2O2==2H2O+O2↑
    68                       32                        x =3.4g                                                       x                        1.6g
   3.4/0.03 ≈113.3g            
 
 
Zn +H2SO4==ZnSO4+H2↑
65                                2                           x =13g
x                                  0.4g
   Cu %=(20-13)/20=35%
 
 
 
2NaHCO3==Na2CO3+H2O+CO2↑
168                                      44                     x =4.4g
16.8                                       x