Question

Calculate the amount of heat required to completely sublime 40.0g of solid dry ice (CO2) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/mol.

Answer 1

Number of moles of dry ice = 40/44 = X moles

So, 1 mole ----------- 32.3 kJ
X moles ----------- 32.3/X kJ (heat required)

Answer 2

At the last step you want to multiply by moles not divide

32.3 kJ/mol*x moles