A scientist reacts hydrobromic acid with magnesium hydroxide in a glass beaker. As the reaction proceeds, the scientist observes that the glass beaker in which the reaction is taking place in feels warm. Is this an endothermic or exothermic reaction? How do you know? a It is exothermic; heat energy has been released to the surroundings, making the container warm. b It is endothermic; heat energy has been absorbed from the surroundings, making the container warm. c It is exothermic; heat energy has been absorbed from the surroundings, making the container warm. d It is endothermic; heat energy has been released to the surroundings, making the container warm.

Answer 1

a It is exothermic; heat energy has been released to the surroundings, making the container warm.

Exothermic reactions release heat energy to the surroundings, causing the container to feel warm. In this case, the warmth of the glass beaker indicates that heat is being given off during the reaction, making it exothermic.