chemistry question about PE & forward reaction

Question

Given the following information about a forward reaction:

Heat of reactants is 100kJ

Heat of products is 20kJ

Heat of activated complex is 150 kJ

Activation energy for the uncatalyzed reaction is 50kJ

Heat of reaction (delta H) is -80kJ

If the forward reaction is carried out in a tub of water at 25C, will the temperature of the water increase or decrease? Why?

Will this forward reaction occur if the reactants were given 40kJ of activation energy? Explain.

Answer 1

Because the heat of the products is less than the heat of the reactants, this tells us the reaction is exothermic, meaning it will release heat to the surroundings. Thus, the temperature of the water will increase.

The activation energy for the forward reaction is the difference between the energy of the reactants (100 kJ) and the heat energy of the activated complex (150 kJ), i.e. Ea forward reaction = 50 kJ. If you supply 40 kJ, that would not be sufficient, so the reaction would not occur.