Final answer:
The change in enthalpy (∆H) for 100.0 g of water cooling from 61.9 °C to 24.1 °C is -15.79 kJ, indicating heat release.
Step-by-step explanation:
The student is asking about the change in enthalpy (∆H) when 100.0 g of water cools from 61.9 °C to 24.1 °C at constant pressure. Enthalpy change can be calculated using the formula ∆H = mc∆T, where m is the mass of the water, c is the specific heat capacity of water (4.184 J/g°C), and ∆T is the temperature change. The temperature change (∆T) is 61.9 °C - 24.1 °C, equaling 37.8 °C. Hence, the calculation for the enthalpy change is as follows:
∆H = mc∆T = (100.0 g)(4.184 J/g°C)(-37.8 °C)
We include a negative sign because the temperature decrease means heat is released from the water. Converting to kilojoules, the change in enthalpy for the water = (100.0 g)(4.184 J/g°C)(-37.8 °C) / 1000 = -15.79 kJ. This is the absolute value; to indicate heat release, it's written as a negative value.