Question

Greyish metal when reacted with an acid (at room temperature) and a base (on warming) separately produce a gas, which burns with a pop sound. The gas formed when bubbled through a soap solution forms soap bubbles, which rise up in the air. Answer the following: 1. Name the greyish metal and the gas evolved. 2. Write the chemical equations for the reaction of the metal with (i) dilute sulphuric acid (ii) Warm sodium hydroxide solution. 3. Why do soap bubbles rise in the air?

Answer 1

The greyish metal is zinc and the evolved gas is hydrogen.

• The chemical equations will be -

1) Zn + HCl (dil.) ----> ZnCl2 + H2

In this chemical reaction,the zinc metal reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen gas.

2) Zn + NaOH ----> Na2ZnO2 + H

In this chemical reaction,the zinc metal reacts with extremely warm sodium hydroxide to produce sodium zincate and hydrogen gas.

• Hydrogen gas is lighter than the air, that's why bubbles of hydrogen gas rise in the air.