Question

An organic compound A on heating with concentrated H2SO4 forms a compound B, which on the addition of one mole of hydrogen in the presence of Ni forms a compound C. One mole of compound C, on combustion, forms two moles of CO2 and 3 moles of H2O. Identify the compounds A, B, and C and write the chemical equations of the reactions involved.

Answer 1

The organic compounds A, B, and C are ethanol, ethene, and ethane respectively. The reactions include the dehydration of ethanol to ethene, hydrogenation of ethene to ethane, and the combustion of ethane producing CO2 and H2O.

Step-by-step explanation:

The organic compound A, upon heating with concentrated H2SO4, forms compound B that adds one mole of hydrogen with Ni to form compound C. When one mole of compound C is combusted, it produces two moles of CO2 and three moles of H2O. From this stoichiometry, we can deduce that compound C has two carbon atoms and six hydrogen atoms, which corresponds to the formula C2H6, ethane.

Therefore, working backward, compound B, which gains one mole of hydrogen to form ethane, must be C2H4, ethene. The formation of ethene from an organic compound A by dehydration suggests that A is an alcohol. The corresponding alcohol for ethene is C2H5OH, ethanol. Hence compound A is ethanol.

The reactions can be described by the following chemical equations:

1. Heating ethanol with concentrated H2SO4: C2H5OH → C2H4 + H2O
2. Adding hydrogen to ethene in the presence of Ni: C2H4 + H2 → C2H6
3. Combustion of ethane: 2C2H6 + 7O2 → 4CO2 + 6H2O