Question

when solid ammonium chloride is dissolved in water in a calorimeter, the temperature of the water decreases. which statement is true? a the reaction is endothermic because heat transfers from the water to the solid. b the reaction is exothermic because heat transfers from the solid to the water. c the reaction is endothermic because heat transfers from the solid to the water. d the reaction is exothermic because heat transfers from the water to the solid.

Explanation:

In an endothermic reaction, heat is absorbed by the reactants from the surroundings. Here, solid ammonium chloride dissolving in water makes the water temperature decrease, meaning the solid (reactant) is absorbing heat from the water (surroundings). In an exothermic reaction, heat is released to the surroundings. Since heat is transferred from water to the solid causing the water's temperature to drop, it's an endothermic reaction.

Answer:

a. The reaction is endothermic because heat transfers from the water to the solid.