Final answer:
The ΔHrxn for the dissolution of KF in water is calculated using the mass of the water, specific heat capacity, and temperature change, resulting in -926.76 J, which is option A.
Step-by-step explanation:
The problem involves finding the enthalpy change (ΔHrxn) for the dissolution of potassium fluoride (KF) in water. This is an application of the concept of calorimetry, particularly using the temperature change observed when a known mass of a substance is dissolved in a solvent to calculate the energy change.
To calculate the enthalpy change, the following formula can be used: ΔHrxn = -q = -m · cs · ΔT, where m is the mass of the solvent (water in this case), cs is the specific heat capacity of the solvent, and ΔT is the temperature change of the solution.
The mass of the water is equivalent to its volume since the density (d) is 1.00 g/mL, so m = 595.0 g. The specific heat capacity (cs) assumed is that of water, 4.18 J/g°C, and the temperature increase (ΔT) is 3.91°C. Using these values, we calculate the heat (q) absorbed by the solution, which is also the heat released by the dissolving KF (since the dissolution process caused the temperature to rise).
By substituting the given values into the formula, we get: ΔHrxn = -(595.0 g · 4.18 J/g°C · 3.91°C) = -9269.07 J, which is then rounded according to the significant figures from the mass of KF to -926.76 J (Option A).