Dry ice (solid CO₂) sublimates directly to the gaseous state at –78.5 °C. The molar enthalpy of sublimation of CO₂ at this temperature is 25.2 kJ mol⁻¹.
(a) A laboratory freezer contains a block of dry ice with a mass of 145 g. Calculate the total quantity of heat, in kJ, that must be absorbed by the CO₂ for the entire block to convert to gas at –78.5 °C.
(b) A researcher wants to design an experiment in which exactly 2.50 × 10² kJ of heat is absorbed by sublimating dry ice at –78.5 °C. Determine the mass of solid CO₂ (in grams) that must sublime to absorb this amount of energy. Express your answer with the correct number of significant figures.