Question

Dissolving 3.0 g of CaCl₂(s) in 150.0 g of water in a calorimeter at 22.4 °C causes the temperature to rise to 25.8 °C. What is the approximate amount of heat involved in the dissolution, assuming the specific heat of the resulting solution is 4.18 J/g °C? Is the reaction exothermic or endothermic?

a) −66.8J, exothermic
b) 66.8J, endothermic
c) −66.8J, endothermic
d) 66.8J, exothermic

Answer 1

The approximate amount of heat involved in the dissolution of CaCl₂ in water is 2138.2 J. The reaction is exothermic.

Step-by-step explanation:

The amount of heat involved in the dissolution can be calculated using the formula q = m * C * ΔT, where q is the heat involved, m is the mass of the solution, C is the specific heat of the solution, and ΔT is the change in temperature. In this case, the mass of the solution is 150.0 g of water, the specific heat of the solution is 4.18 J/g °C, and the change in temperature is (25.8 °C - 22.4 °C) = 3.4 °C.

Plugging these values into the formula, we get q = (150.0 g) * (4.18 J/g °C) * (3.4 °C) = 2138.2 J.

The reaction is exothermic because the temperature of the solution increased, indicating a release of heat.