To calculate the standard enthalpy change for the reaction, we first need to determine the heat released or absorbed during the reaction. We can do this using the formula:q = mcTwhere q is the heat released or absorbed, m is the mass of the solution, c is the specific heat capacity, and T is the change in temperature.First, let's find the limiting reactant. Since the reaction between HCl and NaOH is a 1:1 reaction, we can determine the limiting reactant by comparing the moles of each reactant:moles of HCl = 25.0 mL 0.100 mol/L = 2.50 mmolmoles of NaOH = 25.0 mL 0.200 mol/L = 5.00 mmolSince there are fewer moles of HCl, it is the limiting reactant. The reaction will consume all 2.50 mmol of HCl and 2.50 mmol of NaOH, leaving 2.50 mmol of NaOH unreacted.Now, let's calculate the heat released or absorbed during the reaction. Since the reaction is exothermic, the heat released will be negative. The enthalpy change for the reaction between HCl and NaOH is -57.3 kJ/mol. We can calculate the heat released for the 2.50 mmol of HCl and NaOH that react:q = - 2.50 mmol 57.3 kJ/mol = -143.25 kJNow, we need to calculate the mass of the solution. Since the density of both solutions is 1.00 g/mL, the mass of the solution is:mass = 25.0 mL HCl + 25.0 mL NaOH 1.00 g/mL = 50.0 gNow, we can use the formula q = mcT to find the change in temperature:T = q / mc = -143.25 kJ / 50.0 g 4.18 J/gC Note that we need to convert kJ to J:T = -143,250 J / 50.0 g 4.18 J/gC = -684.7CFinally, we can calculate the standard enthalpy change for the reaction:H = q / moles of limiting reactant = -143.25 kJ / 2.50 mmol = -57.3 kJ/molThe standard enthalpy change for the reaction is -57.3 kJ/mol.