Elements of Group 1 and 2 — Chemistry STD 11 Science — Question
Maharashtra BoardEnglish MediumSTD 11 ScienceChemistryElements of Group 1 and 23 Marks
Question
What happens when dihydrogen reacts with halogens?
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Answer
$i.$ Dihydrogen reacts with halogens $(X_2)$ to give the corresponding hydrogen halides $(HX).$
$\underset{\text { Hydrogen }}{ H _{2( g )}}+\underset{\text { Halogen }}{ X _{2( g )}} \longrightarrow\underset{\text { Hydrogen halide }}{2 HX _{( g )}}($where, $X = F , Cl , Br , I )$
$ii.$ Dihydrogen reacts with fluorine to form hydrogen fluoride even at very low temperature $(-250^\circ C)$ in dark.
$\underset{\text { Hydrogen }}{ H _{2( g )}}+\underset{\text { Fluorine }}{ F _{2( g )}} \longrightarrow\underset{\text { Hydrogen fluoride }}{2 HF }$
$iii.$ However, the reaction with iodine requires a catalyst as the vigour of reaction of dihydrogen decreases with increasing atomic number of halogen.
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