Question

Fluorine reacts with water to form:
(A) $\text{HF}\,\text{and }{{\text{O}}_{\text{2}}}$
(B) $\text{HF}\,\text{and }{{\text{O}}_{3}}$
(C) $\text{HF}\,\text{and O}{{\text{F}}_{\text{2}}}$
(D) $\text{HF,}\,{{\text{O}}_{2}}\,\text{and }{{\text{O}}_{3}}$

Answer 1

Hint: Halogen are very reactive due to high electronegativity, high electron affinity and comparatively low bond energies.
- Fluorine has the highest reduction potential hence it is the strongest oxidizing agent.

Complete step by step answer:
- Fluorine and chlorine reacts with water while bromine and iodine are only sparingly soluble in water.
Fluorine gas reacts with water in normal temperature form hydrogen fluoride $\text{(HF)}$ and release oxygen gas $\text{(}{{\text{O}}_{\text{2}}}\text{)}$, $\text{2}{{\text{F}}_{\text{2(g)}}}\text{+}\,\text{2}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{(l)}}}\to \,\text{4F}_{\text{(aq)}}^{\text{-}}\,\text{+}\,\text{4}\,\text{H}_{\text{(aq)}}^{\text{+}}\text{+}\,{{\text{O}}_{\text{2(g)}}}\,$
- When a large amount of fluorine gas is reacted with water molecule at very high temperature, it will release ozone gas with $\text{HF}$
$\text{3}{{\text{F}}_{\text{2(g)}}}\text{+}\,3{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{(l)}}}\to \,\text{4F}_{\text{(aq)}}^{\text{-}}\,\text{+}\,\text{4}\,\text{H}_{\text{(aq)}}^{\text{+}}\text{+}\,{{\text{O}}_{\text{3(g)}}}\,$
When fluorine reacts with water in the presence of sunlight at very low temperature it forms $\text{HOF}$ and $\text{HF}$.
${{\text{F}}_{\text{2}}}\text{+}\,{{\text{H}}_{\text{2}}}\text{O}\xrightarrow[-{{40}^{\circ }}C]{hv}\,\text{HOF}\,\text{+}\,\text{HF}\,\,$
So, the correct answer is “Option A”.

Additional information: Halogen reacts with water in a very different manner. Fluorine oxidises water molecules by releasing oxygen gas. Chlorine and bromine react with water molecules to form hydra acid$\text{(HX)}$ and hypohalous acid $\text{(HOX)}$.
${{\text{X}}_{\text{2}}}\text{+}\,{{\text{H}}_{\text{2}}}\text{O}\to \,\text{HOX}\,\text{+}\,\text{HX}\,\,\text{ }\!\!\{\!\!\text{ X=}\,\text{Cl, Br }\!\!\}\!\!\text{ }$
- Iodine does not react with water, instate \[{{\text{I}}^{-}}\] ions can be oxidised by oxygen in an acidic medium.

Note: Hydride of fluorine $\text{HF}\,$ is liquid because of strong hydrogen bonding ,while other halogen hydracids $\text{(HX)}$ are gaseous in nature. The abnormal behaviour of fluorine is due to its small size, high electronegativity and low $\text{F-F}$ bond dissociation energy.
- Fluorine forms only one oxyacid $\text{HOF}$, because of its high electronegativity and small size and represents only one covalency.