Question

Which of the following is an exothermic reaction?

A
concentrated hydrochloric acid dissolving in water
B
ammonium nitrate dissolving in water
C
ammonium chloride dissolving in water
D
sugar dissolving in water

Answer 1

Concentrated hydrochloric acid dissolving in water is an exothermic reaction, as it releases heat during the process. The correct answer is A.

Step-by-step explanation:

The student asked which of the following is an exothermic reaction:

• Concentrated hydrochloric acid dissolving in water
• Ammonium nitrate dissolving in water
• Ammonium chloride dissolving in water
• Sugar dissolving in water

In this context, an exothermic reaction releases heat to its surroundings. Among the options provided, concentrated hydrochloric acid dissolving in water is an exothermic process because it releases heat as it dissolves. The correct answer is therefore A. When hydrochloric acid (HCl) is added to water, it releases heat as the strong acid dissociates into H+ and Cl- ions.

It is important to note that the dissolution of ammonium chloride (NH4Cl) is an endothermic process, meaning it absorbs heat and, as a result, the solution feels cold to the touch. This is not to be confused with exothermic processes.

Answer 2

A. concentrated hydrochloric acid dissolving in water

Step-by-step explanation:

• Chemical reactions may be classified as either exothermic or endothermic. Exothermic reactions are those that release heat energy to the surrounding while endothermic reactions are those that absorb heat from the surrounding.
• Exothermic reactions includes dissolving an acid in water. For example dissolving Concentrated HCl in water is exothermic as heat is released to the surroundings. The amount of heat released depends on the strength of an acid.