To calculate the amount of heat required for subliming 20 g of iodine, we first need to determine the number of moles of iodine present in 20 g. The molar mass of iodine I2 is approximately 253.8 g/mol.Number of moles = mass / molar massNumber of moles = 20 g / 253.8 g/mol = 0.0788 molNow, we can use the heat of sublimation 62.44 kJ/mol to calculate the amount of heat required to sublime this amount of iodine.Heat required = number of moles heat of sublimationHeat required = 0.0788 mol 62.44 kJ/mol = 4.92 kJTherefore, the amount of heat required for subliming 20 g of iodine at its melting point of 387 K is approximately 4.92 kJ.