怎样鉴别NaNO2和NaCl 要用化学方法 方法

2025-04-07 06:59:31
推荐回答(1个)
回答(1):

  1. 稀AgNO3和稀硝酸   利用Cl-及NO2-和Ag+反应生成白色沉淀是否溶于稀HNO3

    Ag++Cl-=AgCl↓  Ag++ NO2-=AgNO2↓  AgNO2+HNO3=AgNO3+HNO2 

  2. 酚酞溶液或pH试纸  利用NaNO2溶液水解呈碱性,能使酚酞变浅红,而NaCl溶液呈中性。用pH试纸检验溶液的pH值也可以。

    NO2-+H2O≒HNO2+OH-  

  3. 试管里加入少量待检盐,加几滴盐酸或稀硫酸或食醋,出现红棕色气体的是NaNO2。

    NaNO2+H2SO4 = NaHSO4+HNO2 ,  2HNO2 =NO↑+NO2↑+H2O

  4. 加入KMnO4溶液(酸性溶液)  利用NO2-的还原性

    5 NO2- +2MnO4-+6H+ =5 NO3- +2Mn2+ +3H2O 

  5. 加入KI淀粉  利用NO2-的氧化性

    2 NO2-+2I-+4H+ =2NO+I2+2H2O

  6. 加入(NH4)2Fe(SO4)2溶液  利用NaNO2的氧化性  

    NO2-+Fe2++2H+=NO+Fe3++H2O

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