Question

Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.

Answer 1

The lustrous divalent element M can be an amphoteric metal like Zn, Sn or Pb etc. When zinc is treated with sodium hydroxide it forms sodium zincate and hydrogen gas. When zinc is treated with hydrochloric acid it forms zinc chloride and hydrogen gas, and that is why Iqbal made the same observation.

`2"NaOH"("aq") + "Zn"("s") overset("Heat")(->)"Na"_2"ZnO"_2("aq") + "H"_2("g")`

`2"HCl"("aq") + "Zn"("s") -> "ZnCl"_2("aq") + "H"_2("g")`

To test the hydrogen gas produced in the chemical reaction, if a glowing splint in brought near the gas produced then it would burn with a pop sound.