To calculate the enthalpy change, we first need to determine the number of moles of NaOH in 5 grams.The molar mass of NaOH is:Na = 22.99 g/molO = 16.00 g/molH = 1.01 g/molTotal = 22.99 + 16.00 + 1.01 = 40.00 g/molNow, we can find the number of moles of NaOH in 5 grams:moles = mass / molar massmoles = 5 g / 40.00 g/mol = 0.125 molNow, we can use the molar enthalpy of dissolution to find the enthalpy change:enthalpy change = moles molar enthalpy of dissolutionenthalpy change = 0.125 mol -44.5 kJ/mol = -5.5625 kJThe enthalpy change of dissolving 5 grams of sodium hydroxide in 100 mL of water at 25C is -5.5625 kJ.