Question

Calculate the amount of heat required to completely sublime 96.0 gg of solid dry ice (CO2)(CO2) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/molkJ/mol. Express your answer in kilojoules.

Answer 1

The correct answer is 70.41 kJ ≅ 70.4 kJ

Step-by-step explanation:

The heat required to sublimate the solid at its sublimation temperature is calculated by using the following formula:

heat = ΔHs x moles of substance

Where ΔHs is the heat of sublimation, which is known (32.3 kJ/mol).

So, we have to calculate the moles of substance. For this, we can divide the mass of substance by the molecular weight of substance (CO₂):

mass CO₂ = 96.0 g

molecular weight CO₂ = (12 g/mol x 1) + (16 g/mol x 2) = 44 g/mol

⇒ moles of CO₂ = mass CO₂/molecular weight CO₂ = (96.0 g)/(44 g/mol) = 2.18 moles

Finally, we use the first formula to calculate the heat:

heat = ΔHs x moles = 32.3 kJ/mol x 2.18 mol = 70.41 kJ ≅ 70.4 kJ