To calculate the standard enthalpy change for the fusion reaction of 2.5 grams of ice at 0 degrees Celsius, we need to use the formula:H = m Hfuswhere H is the enthalpy change, m is the mass of the ice, and Hfus is the enthalpy of fusion for water.The enthalpy of fusion for water is 6.01 kJ/mol the energy required to convert 1 mole of ice to water at 0 degrees Celsius .First, we need to convert the mass of ice 2.5 grams to moles. The molar mass of water H2O is 18.015 g/mol.moles of ice = 2.5 g / 18.015 g/mol = 0.1387 molNow, we can calculate the enthalpy change:H = 0.1387 mol 6.01 kJ/mol = 0.833 kJThe standard enthalpy change for the fusion reaction of 2.5 grams of ice at 0 degrees Celsius is 0.833 kJ.