Process Change - Enthalpy and Entropy Question

Question

Considering the following processes, which would give the greatest increase in both enthalpy and entropy change?

Choices include:

deposition, sublimation, melting, condensation or vaporization.

Answer 1

Consider each process and how it affects enthalpy (heat) and entropy (how chaotic or neat a system is)

ΔH = enthalpy; positive (+) = endothermic (absorbs heat, inputs heat); negative (-) releasees heat

ΔS = entropy; positive (+) = increase in entropy; negative (-) = decrease in entropy

solid --> liquid ---> gas is all increases in entropy. The molecules are moving faster and are more disordered and spread apart. This set also has positive enthalpy as heat is inputted to heat the molecules and change phase.

gas ---> liquid ---> solid are all decreases in entropy. The molecules are becoming neater and aligned as you move towards the solid. There would also be a negative enthalpy as this set of changes are exothermic.

types of phase changes:

solid ---.> liquid = melting

liquid --> gas = vaporization

solid ---> gas = sublimation

gas ---> solid = deposition

gas ---> liquid = condensation

liquid ---> solid = freezing

Considering all the processes, the greatest increase would be sublimation as the solid changes to a gas. This process would have a high enthalpy (+) and this process would have a high entropy (+). This would be the highest as the solid directly changes into the gas phase.