Question

Given a sample of dry ice (solid CO2) with a mass of 50 grams, calculate the amount of heat energy that needs to be added to sublimate it completely into gaseous CO2 at a temperature of -78.5°C. The heat of sublimation of CO2 is 25.2 kJ/mol. (Assume that CO2 is an ideal gas under these conditions.)

Answer 1

To calculate the amount of heat energy needed to sublimate the dry ice, we first need to determine the number of moles of CO2 in the 50-gram sample. The molar mass of CO2 is 12.01 g/mol  C  + 2 * 16.00 g/mol  O  = 44.01 g/mol.Number of moles = mass / molar massNumber of moles = 50 g / 44.01 g/mol  1.136 molesNow, we can use the heat of sublimation  25.2 kJ/mol  to calculate the amount of heat energy required to sublimate the entire sample.Heat energy = number of moles * heat of sublimationHeat energy = 1.136 moles * 25.2 kJ/mol  28.63 kJTherefore, approximately 28.63 kJ of heat energy needs to be added to the 50-gram sample of dry ice to sublimate it completely into gaseous CO2 at a temperature of -78.5C.