To calculate the enthalpy involved when two solutions are mixed, we can use the equation:
q = mcΔT
where q is the heat transferred, m is the mass of the solution, c is the specific heat capacity of the solution, and ΔT is the change in temperature.
First, we need to determine the mass of the solution. Since the density of the solutions is close to 1.00 g/mL, we can assume that the mass of each solution is equal to its volume (200 mL = 200 g). Therefore, the total mass of the solution is 400 g.
Next, we calculate the change in temperature (ΔT) by subtracting the initial temperature from the highest temperature reached:
ΔT = 31.0°C - 24.5°C = 6.5°C
Now, we can calculate the enthalpy change using the formula:
q = mcΔT
q = (400 g) x (4.184 J/g°C) x (6.5°C)
q = 108,806 J
So, the enthalpy change involved when the two solutions are mixed is 108,806 J.