Question

When aqueous solutions of HCl and NaOH are mixed together in a calorimeter, the temperature of the solution increases. The reaction is

endothermic, causing an increase in the kinetic energy of the solute particles.

endothermic, causing an increase in the kinetic energy of the water molecules.

exothermic, causing an increase in the kinetic energy of the water molecules.

exothermic, causing an increase in the kinetic energy of the solute particles.

Answer 1

The prefixes "exo-" and "endo-" live on in the ordinary English words "exit" and "entrance." Does that clue you in?

Answer 2

You also need to keep in mind that the "system" here is the reacting molecules, and the "surroundings" are the calorimeter and the water it contains. So anything (like heat) coming "out of" the reacting molecules goes into the water, and antying going "into" the reacting molecules must come out of the water.

Answer 3

exothermic