205k views
2 votes
A 0.500-g sample of KCl is added to 50.0 g of water in a calorimeter. If the temperature decreases by 1.05 °C, what is the approximate amount of heat involved in the dissolution of the KCl, assuming the specific heat of the resulting solution is 4.18 J/g °C? Is the reaction exothermic or endothermic?

a) −209J, exothermic
b) 209J, endothermic
c) −209J, endothermic
d) 209J, exothermic

User Makudex
by
7.9k points

1 Answer

5 votes

Final answer:

The heat involved in the dissolution of KCl is calculated using the formula q = mcΔT, yielding a value of approximately 219.45 J. The temperature decrease indicates an endothermic process, so the closest answer available is 209J, endothermic.

Step-by-step explanation:

To calculate the amount of heat involved in the dissolution of KCl, we use the formula: q = mcΔT, where m is the mass of the water, c is the specific heat of the solution, and ΔT is the change in temperature. For a 0.500-g sample of KCl added to 50.0 g of water, with a temperature decrease of 1.05 °C and a specific heat of 4.18 J/g °C, the calculation is as follows:

q = (50.0 g)(4.18 J/g °C)(-1.05 °C), q = -50.0 g × 4.18 J/g °C × -1.05 °C = 219.45 J, Since the temperature decreases, the reaction absorbs heat, indicating that it is an endothermic reaction. Therefore, the closest appropriate answer is (b) 209J, endothermic.

User Turtlepick
by
8.1k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.