Question

lesson 24: systems and energy
which of the following is true about the energy diagram below?
energy diagram with before reaction (system and surroundings) and after reaction (system and surroundings) bars
options:

• the total energy remains the same
• the total energy is less after the reaction
• the reaction is exothermic
• the reaction is endothermic

Explanation:

According to the law of conservation of energy, the total energy of an isolated system (system + surroundings) remains constant. In the energy diagram, we can see that the sum of the energy of the system and surroundings before the reaction is equal to the sum of the energy of the system and surroundings after the reaction. For the nature of the reaction, since the system's energy decreases (from a higher - energy state before the reaction to a lower - energy state after the reaction), the system releases energy to the surroundings. An exothermic reaction is a reaction in which the system releases energy to the surroundings.

Answer:

the total energy remains the same; the reaction is exothermic