Question

1. Iron filings and sulphur powder were mixed together and divided into two parts, A and B. Part A was heated strongly while part B was not heated. Which gas will be evolved when dilute hydrochloric acid is added to part A?

Answer 1

Answer:

As part 'A' is heated, a compound FeS is formed by the reaction between iron filings and sulphur. When dilute HCl is added to part A, FeS will react with dil HCl to form H2S gas which has smell of rotten eggs and will turn lead acetate paper black.

Fe(s)+S(s)−→−HeatFeS(s)

FeS(s)+2HCl(dil.)→FeCl2(aq)+H2S(g)

(CH3COO)2Pb(aq)Lead acetate+H2S(g)→PbS(s)Black ppt+2CH3COOHAcetic acid

As part 'B' in not heated, so B is a mixture of iron fillings and sulphur powder. When dil, HCl is added to it, iron filings react with dill. HCl to form H2(g) which burns with a 'pop' sound if burning match stick is brought near it.

Fe(s)+2HCl(dil.)→FeCl2(aq)+H2(g)

Explanation:

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