Question

The potential energy diagram for a reaction starts at 380 kJ and ends at 100 kJ. What type of reaction does the diagram best represent?
A. Exothermic reaction

B. Endothermic reaction

C. Reaction between two solids

D. Reaction between two liquids

Answer 1

Answer: A.  Exothermic reaction

Explanation: Enthalpy change for a reaction is sum of enthalpy of formation of products minus sum of enthalpy of formation of reactants.

When the energy level of reactants is above as compared to the products, the reaction is exothermic and when its opposite then reaction is endothermic.

From given information, the potential energy diagram starts at 380 kJ means the energy level of reactants is 380 kJ. It ends at 100 kJ means the energy of products is 100 kJ.

Enthalpy of reaction = 100 kJ - 380 kJ

Enthalpy of reaction = -280 kJ

Negative sign of enthalpy change indicates an Exothermic reaction.

Answer 2

Answer:

Exothermic reaction

Explanation:

In a reaction, the potential energy diagram shows the reaction trajectory as reactants are converted into products.

In an exothermic reaction, reactants possess more energy than products hence energy is given out as heat.

If the reaction coordinate starts at 380KJ and ends at 100KJ then energy was given out since products possess less energy than reactants. Hence the answer.