Question

What do we get when ethene is reacted with $ HCl $ ?

Answer 1

Hint: For answering this question we should learn about the additional reaction of Alkenes with Hydrogen halides. We will see the reaction and understand the process behind formation of the product to get the required answer.

Complete answer:
This reaction of Alkenes with halogen is an example of electrophilic addition reaction. The products formed are known as alkyl halides or Vicinal dihalides (also known as gem dihalides). Vicinal dihalides have halogens attached to the adjacent carbons. Let us see the reaction
 $ C{H_2} = C{H_2} + HCl \to C{H_3}C{H_2}Cl $
In the above reaction we can see that Ethene reacts with Hydrochloric acid to produce Chloroethane. Let us understand the mechanism of the reaction
This is an electrophilic addition reaction in which the initial substrate is attacked by the electrophile and it results in addition of a simple atom or molecule across a multiple bond. Hydrogen develops partial positive charge and chlorine develops partial negative charge because electrons in $ H - Cl $ bond are attracted to chlorine which is more electronegative. First the double bond breaks in ethene leaving positive charge and negative charge on carbons, Electrophile is attached to the negative charged carbon and nucleophile gets attached to positively charged carbon this reaction Chlorine acts as nucleophile and Hydrogen bonded to Chlorine acts as electrophile. So Chloroethane is formed.

Note:
Chlorine acts as nucleophile and is attached to the carbon which has positive charge, it has donated the electrons to other carbon (electrons involved in broken double bond) and Hydrogen is attached to the other carbon which has negative charge, this carbon accepts the donated electrons.