A carbon compound ‘P’ on heating with excess conc. H 2 SO 4 forms another carbon compound ‘Q’ which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound ‘R’. One molecule of ‘R’ on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equations for the reactions involved.
Answer:
- On combustion, compound R forms carbon dioxide and water. So, R is an alkane. Since 2 molecules of carbon dioxide are formed, R is an alkane with 2 carbon atoms.
Therefore, R is Ethane.
- When hydrogen is added to compound Q in the presence of a nickel catalyst, ethane is formed. Ethane is a saturated hydrocarbon. Hydrogenation of unsaturated carbon compounds gives saturated hydrocarbons. Therefore, Q is an unsaturated carbon compound with 2 carbon atoms.
So, Q is Ethene.
- When alcohols are heated in the presence of conc H 2 SO 4 , dehydration reaction takes place and alkenes are formed. When compound P is heated in the presence of conc H 2 SO 4 , Ethene is formed. So, P is an alcohol with 2 carbon atoms.
Therefore, P is Ethanol.
Therefore,
- Compound P is Ethanol
- Compound Q is Ethene
- Compound R is Ethane
The reactions that take place are:
Reaction of Ethene with Hydrogen:
