Question

Which statement correctly describes an endothermic chemical reaction?

(1) The products have higher potential energy than the reactants,and the ΔH is negative.(2) The products have higher potential energy than the reactants, andthe ΔH is positive.(3) The products have lower potential energy than the reactants, andthe ΔH is negative.(4) The products have lower potential energy than the reactants, andthe ΔH is positive.

Answer 1

Answer: The correct answer is Option 2.

Explanation: There are 2 types of reactions classified under the change of energy in a system:

1. Endothermic reactions: These are defined as the chemical reactions in which energy is absorbed in a system. The potential energy of the products is more than the potential energy of the reactants. As energy is absorbed in the system, so
`\Delta H=+ve`

2. Exothermic reactions: These are defined as the chemical reactions in which energy is released by the system. The potential energy of the products is less than the potential energy of the reactants. As energy is released by the system, so
`\Delta H=-ve`

From the given information above, we can conclude that in endothermic chemical reaction, the products have higher potential energy than the reactants, and ΔH is positive. Hence, the correct answer is option 2.

Answer 2

Answer is: (2) The products have higher potential energy than the reactants, and the ΔH is positive.

There are two types of reaction:

1) endothermic reaction (chemical reaction that absorbs more energy than it releases, ΔH>0).

2) exothermic reaction (chemical reaction that releases more energy than it absorbs).

For example, the breakdown of ozone is an endothermic process. Ozone has lower energy than molecular oxygen (O₂) and oxygen atom, so ozone need energy to break bond between oxygen atoms.