It seems there's a small error in the provided information. The temperature *decreases* from 30.5°C to 35.6°C. This is not possible in a typical dissolution process.

Here's why:

* Dissolving salt (NaCl) in water is usually an endothermic process. This means heat is absorbed from the surroundings, causing the temperature of the solution to decrease.

* Temperature cannot decrease and then increase simultaneously. If the temperature decreased from 30.5°C, it could not then increase to 35.6°C within the same process.

To calculate the enthalpy change (ΔH) of the reaction, we need the correct temperature change.

Here's how we'd approach the calculation if we had the correct temperature data:

1. Calculate the change in temperature (ΔT): ΔT = Final Temperature - Initial Temperature

2. Determine the mass of the solution: Since the density of water is approximately 1 g/mL, the mass of 1000 mL of water is 1000 g. Add the mass of the salt (50 g) to get the total mass of the solution (1050 g).

3. Use the specific heat capacity of water: The specific heat capacity of water is approximately 4.184 J/g°C.

4. Calculate the heat change (q): q = mass of solution × specific heat capacity × ΔT

5. Relate heat change to enthalpy change: Since the process is at constant pressure, the heat change (q) is equal to the enthalpy change (ΔH) of the reaction.

Remember: If the final temperature is lower than the initial temperature, the enthalpy change (ΔH) will be positive, indicating an endothermic reaction. If the final temperature is higher, the enthalpy change will be negative, indicating an exothermic reaction.