Question

consider a nypothetical chemical reaction: A+B +C+D (In this equation A, B, C and D stand for some unknown chemical formulas.) Here is an energy diagram for the reaction: 400+ A + B 300+ energy (kJ/mol) 200+ C +D reaction coordinate Use the energy diagram to answer these questions. What is the heat of reaction? kJ/mol Exothermic Is the reaction exothermic or endothermic? Endothermic Can you determine the activation energy? ONeither Yes, it's kJ/mol O No. Yes, it's ] kJ/mol No. Can you determine the activation energy of the reverse reaction? C+D +A+B

Answer 1

1. Heat of the reaction = energy of product - energy of reactant

(100-300)Kjmol-1 = -200Kjmol-1 where negative sign shows energy is released in the process

2. Since the product is more stable( as having lower energy) than the reactant(having higher energy), this implies that the heat must be released in the process or reaction which suggests that the reaction is EXOTHERMIC.

3. The activation energy for forward or given reaction is,

= ( energy of transition state - energy of reactant)

= (400-300) Kj/mol

= 100 Kj/mol, Yes we can determine the activation energy.

4. The activation energy for backward or given reaction is,

= ( energy of transition state - energy of product)

= (400-100) Kj/mol

= 300 Kj/mol, Yes we can determine the activation energy for backward reaction also.