Step-by-step explanation:
In an exothermic reaction the energy of the products is lower than the energy of the reactants, and the excess of energy is released to the surroundings. In our problem, the energy of the reactants is 30 kJ and the energy of the products is 5 kJ, then our reaction is exothermic. With this information we can also find the enthalpy change of this reaction.
Potential energy of the products = 5 kJ
Potential energy of the reactants = 30 kJ
Enthalpy change of reaction = energy of products - energy of reactants
Enthalpy change of reaction = 5 kJ - 30 kJ
Enthalpy change of reaction = -25 kJ
Since ΔH of reaction < 0 ----> exothermic
The activation energy is the extra energy that the reactants will need in order to cross the energy barrier to become products. The maximum energy of the system during the reaction was 40 kJ. So the reactants had to reach that "point" of energy to become products. The difference between that point and the energy of the reactants is the activation energy.
activation energy = maximum energy of the system - energy of the reactants
activation energy = 40 kJ - 30 kJ
activation energy = 10 kJ
Answers:
Enthalpy change of reaction = -25 kJ
ΔH of reaction < 0 ----> exothermic
Activation energy = 10 kJ