(1)
Zn的质量 = 20*(1-35%) = 13g
Zn + H2SO4 → ZnSO4+ H2↑
65.2
13g.m(H2)
所以65/13 = 2/m(H2)
解得m(H2) = 0.4g
所以氢气的体积 = 0.4/0.09 = 4.44L
(2)
2H2 + O2 == 2H2O
4.32
m(H2)...1.6g
所以4/m(H2) = 32/1.6
解得m(H2) = 0.2g
Zn + 2HCl→ ZnCl2+ H2↑
65.2
m(Zn).0.2g
所以65/m(Zn) = 2/0.2
解得m(Zn) = 6.5g
所以金属锌的纯度 = 6.5/7 * 100% = 92.9%
(3)
Mg+H2SO4=MgSO4+H2↑
24.2
m(Mg).0.2g
所以24/m(Mg) = 2/0.2
解得m(Mg) = 2.4g
所以镁条的纯度 = 2.4/4 * 100% = 60%