钠先跟水反应2Na+2H2O====2NaOH+H2↑生成氢氧化钠后才与硫酸铜反应CuSO4+2NaOH===Cu(OH)2↓+Na2SO4
2Na+2H2O=2NaOH+H2CuSO4+2NaOH=Cu(OH)2+Na2SO4
2Na+2H2O====2NaOH+H2↑CuSO4+2NaOH===Cu(OH)2↓+Na2SO4
据调查，2L的正确
CuSO4+2Na=Cu=Na2So4
