To calculate the heat required to sublimate 55 grams of dry ice, we need to use the formula:q = n * H_subwhere q is the heat required, n is the number of moles of the substance, and H_sub is the heat of sublimation.First, we need to find the number of moles n of CO2. The molar mass of CO2 is approximately 44.01 g/mol 12.01 g/mol for carbon and 16.00 g/mol for each oxygen atom .n = mass / molar massn = 55 g / 44.01 g/moln 1.25 molNow we can calculate the heat required q using the heat of sublimation H_sub given as 25.2 kJ/mol.q = n * H_subq = 1.25 mol * 25.2 kJ/molq 31.5 kJTherefore, the heat required to sublimate 55 grams of dry ice at -78.5C and atmospheric pressure is approximately 31.5 kJ.