Question

Pratyush took a sulfur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in the figure below.

(a) What will be the action of gas on (i) dry litmus paper? (ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

Answer 1

(a) Sulphur dioxide (SO₂) is created when sulphur is burnt in the presence of air.

(i) Since sulphur dioxide is a neutral gas, dry litmus paper does not alter when exposed to it.

(ii) Because sulphur dioxide is acidic by nature, it turns blue litmus paper red.

(b) The chemical equation is:

$\mathrm{S}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{SO}}_2\left(\mathrm{g}\right)$