To calculate the standard enthalpy change for the vaporization of 25.0 g of water, we need to first determine the number of moles of water and then use the molar enthalpy of vaporization.1. Calculate the number of moles of water:The molar mass of water H2O is 18.015 g/mol. moles of water = mass of water / molar mass of watermoles of water = 25.0 g / 18.015 g/molmoles of water 1.387 moles2. Calculate the standard enthalpy change:Standard enthalpy change = moles of water molar enthalpy of vaporizationStandard enthalpy change = 1.387 moles 40.7 kJ/molStandard enthalpy change 56.4 kJThe standard enthalpy change for the vaporization of 25.0 g of water at 100C is approximately 56.4 kJ.