Question

In the reaction scheme, a compound with the molecular formula C,H,Br is converted. Identify the reagents and products formed in each step.

Answer 1

To analyze a reaction scheme for a compound with molecular formula C2H4Br2, identify the bonds broken and formed, look at different types of reactions like addition or halogenation, and use bond dissociation energies to calculate enthalpy changes.

Step-by-step explanation:

To understand a reaction scheme, identify the bonds broken in the reactants and formed in the products. For a compound with the molecular formula C2H4Br2, the reaction under consideration likely involves ethene (C2H4) reacting with Br2. Consider the bonds broken: one H-H bond and one Br-Br bond. Bonds formed are two H-Br bonds.

In the steps provided, each reaction is different:

• a. H2 (Ni catalyst) suggests addition of H2 across the double bond of but-2-ene, reducing it to butane.
• b. Br2 suggests a halogenation reaction, where Br2 adds across the double bond of but-2-ene, yielding 2,3-dibromobutane.
• c. H2O (H2SO4 catalyst) suggests hydration where water adds across the double bond forming alcohols through an electrophilic addition mechanism, yielding butan-2-ol.

To calculate the enthalpy change, use bond dissociation energies. Reactant bond dissociation energy may be given in kcal/mol, requiring proper identification and summation of energies for an accurate enthalpy change calculation.