A student dissolves 10.3 g of potassium chloride (KCI) in 200. g of water in a well-insulated open cup. She then observes the temperature of the water fall from 22.0 °C to 19.0 °C over the course of 6.8 minutes. KCI(8) → K+ (aq) + Cl- (aq)

You can make any reasonable assumptions about the physical properties of the solution. Be sure answers you calculate using measured data are rounded to the correct number of significant digits.

Required:
Is this reaction exothermic, endothermic, or neither?

Endothermic.

Explanation:

Hello there!

In this case, it is possible to answer to the requested question "Is this reaction exothermic, endothermic, or neither?" by looking at the temperature change; thus, since the temperature is diminished from 22.0 °C to 19.0 °C, it is possible to realize that the dissociation reaction:

KCI(8) --> K+ (aq) + Cl- (aq)

Is endothermic as it absorbs heat and therefore the solution gets cooled down. Now for any calculation regarding the heat of reaction, it'd be necessary to assume that the solution has a specific heat equal to the water as the former is mostly composed by the latter and the amount of KCl does not modify the solution significantly.

Best regards!

- decrease the number of plants and animals living in the water.