Why are Zn and PB compounds not distinguishable upon addition of NaOH solution? (1 mark).

Asked by bjayanta | 14th Nov, 2016, 09:46: PM

Expert Answer:

Certain metals like Zinc, Aluminium and Lead react with only hot caustic NaOH/KOH solution to give the corresponding soluble salt with the liberation of hydrogen gas.

Metal         +     Alkali                    →        Salt                         +            Hydrogen

1.Zinc     

    Zn         +   2NaOH                    →         Na2ZnO2                  +            H2

                                                                                         Sodium zincate

                                                                   (Colourless)

2.Aluminium

  Al            + 2NaOH   + 2H2O      →         2NaAlO2                  +            H2

                                                            Sodium meta aluminate

                                                                 (Colourless)

 

3. Lead

Pb         +   2NaOH                    →         Na2PbO2                  +            H2

                                                                                    Sodium plumbate

                                                               (Colourless)

 
So upon additon of excess NaOH/KOH these compounds are not distinguishable.

Answered by Vaibhav Chavan | 15th Nov, 2016, 06:02: PM

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