Question

A carbon compound P on heating with excess conc.H2So4 forms another compound Q , which on addition of hydrogen in presence of nickel catalyst forms a saturated compound R . One molecule of R on combustion forms 2 molecules of Co2 and 3 molecules of water . Identify P,Q,R and write equations for reactions involved .

Answer 1

1.Dehydration reaction:
C2H5OH. -----> CH2=CH2 + H2O
compound P is Ethanol. compound Q is Ethene.

2. CH2=CH2 + H2 ---> C2H6
compound R is Ethane
3.C2H6 + O2. ----->2 CO2 + 3H2O + heat + light energy
but Balanced equation is
2C2H6 + 7O2 -----> 4CO2 + 6 H2O

Answer 2

Explanation:

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Q on reacting with hydrogen in presence of catalyst forms a saturated compound. Hence, Q will be an unsaturated compound. P is an alcohol which on dehydration with conc. H_2SO_4H

2 SO 4

forms an alkene. Alkene on combustion forms CO_2CO 2 and H_2OH2 O

P:- CH_3CH_2OHCH 3 CH 2 OH

Q:- CH_2 = CH_2CH

2 =CH 2

R:- CH_3CH_3CH 3 CH 3

CH2 OH →conc.H 2 SO 4 CH 2 =CH 2 +H 2 O

CH_2 = CH_2 + H_2 \overset{Ni}{\rightarrow} CH_3CH_3 CH 2

=CH 2 +H2→Ni CH 3 CH 3

CH 3CH 3 +O 2 →2CO 2 +3H2 O