Question

Which would you expect to have higher enthalpy of fusion, N2 or I2? Explain your choice.

Answer 1

The enthalpy of fusion of a substance is the energy required to change the state of a substance from solid to liquid at a constant temperature. The enthalpy of fusion for iodine, I₂, will be higher. This is because there are stronger intermolecular forces holding the iodine molecules together. The stronger intermolecular forces arise from the fact that iodine is a much larger molecule, so it has much more electrons resulting in higher Van der Waal's forces. This is also visible in the fact that at room temperature, iodine is a solid while nitrogen is a gas.<span />