Question

0 give a chemical test to distinguish between saturated and unsaturated hydrocarbons

Answer 1

$\bold{HYDROCARBONS}$

Hydrocarbons are the compounds which have hydrogen and carbon

They are of two types :--

◼$\bold{SATURATED}$

✳Alkane

They are the compounds which have single bond among carbon atoms.

◼$\bold{UNSATURATED}$

✳Alkene

They are the compounds which have double bond among carbon atoms.

✳Alkyne

They are the compounds which have thriple bond among carbon atoms.

$\bold{TO \: DISTINGUISH \: BETWEEN \: SATURATED \: AND UNSATURATED }$

Saturated hydrocarbon alkane can be distinguish by unsaturated hydrocarbon alkenes and alkynes we use..

◼BROMINE WATER

▶When bromine is added to saturated hydrocarbons (alkanes) under diffused sunlight solution , it by substitution reaction will replace hydrogen atoms with bromine .But the reddish brown color of bromide remains unaffected.

Example :- If bromine is added to methane

$CH_4 + Br_2 \longrightarrow CH_3Br + HBr.$

(monobromomethane)

$CH_3Br + Br_2 \longrightarrow CH_2Br_2 + HBr.$

(dibromomethane)

$CH_2Br_2 + Br_2 \longrightarrow CHBr_3 + HBr.$

(tribromomethane)

$CHBr_3 + Br_2 \longrightarrow CBr_4 + HBr.$

(tetrabromomethane)

▶When bromine water is added to unstaturated hydrocarbons , they does addition reaction which means breaking of bonds and addition of an atom.

When a halogen is added its known as halogenation.

✳For aklene

When bromine is added to aklene the double bond of alkene breaks, and bromine gets added to the compound to complete the bonds.

Example :-Ethene

$C_2H_4 + Br_2 \longrightarrow C_2H_4Br_2.$
(1,2 dibromoethane)

✳For alkyne

When bromine is added to aklyne the triple bond bond of alkene breaks into double then to single , and bromine gets added to the compound to complete the bonds.

Example :-Ethene

$C_2H_2 + Br_2 \longrightarrow C_2H_2Br_2.$
(1,2 dibromoethane)

Further

$C_2H_2Br_2 + Br_2 \longrightarrow C_2H_2Br_4.$
(1,1,2,2 tetrabromoethane)