Question

Calculate the amount of heat absorbed or released when 20 grams of dry ice (solid carbon dioxide) is converted to gaseous carbon dioxide at -78.5°C and atmospheric pressure, given the heat of sublimation of dry ice is 25.2 kJ/mol.

Answer 1

To calculate the amount of heat absorbed or released, we need to determine the number of moles of dry ice and then use the heat of sublimation.First, we need to find the molar mass of carbon dioxide  CO2 . The atomic mass of carbon  C  is 12.01 g/mol, and the atomic mass of oxygen  O  is 16.00 g/mol. Therefore, the molar mass of CO2 is:Molar mass of CO2 = 12.01 g/mol  C  + 2 * 16.00 g/mol  O  = 44.01 g/molNow, we can find the number of moles of dry ice  n  using the mass  m  and molar mass  M :n = m / Mn = 20 g / 44.01 g/mol = 0.454 molNow we can use the heat of sublimation  H_sub  to calculate the amount of heat absorbed or released  q :q = n * H_subq = 0.454 mol * 25.2 kJ/mol = 11.44 kJSince the dry ice is being converted from solid to gas, it is absorbing heat. Therefore, the amount of heat absorbed is 11.44 kJ.