Homework 9.45

[aristotelis1H]

"9.45 Use the information in Table 8.3 to calculate the changes in entropy f the surroundings and of the system for (a) the vaporization of 1.00 mol CH₄(l) at its normal boiling point; (b) the melting of 1.00 mol C₂H₅OH(s) at its normal melting point; (c) the freezing of 1.00 mol C₂H₅OH(l) at its normal freezing point"

When solving for part (c) and using

ΔS_sys =

Is the ΔH^o_fus value negative because heat is released from a system when freezing an object?

[Dahriel Aron 3A]

for this problem, I was also wondering why they divide the enthalpy of fusion for ethanol by the freezing point and not the melting point to find its melting entropy

[Jacob Afable 3J]

"9.45 Use the information in Table 8.3 to calculate the changes in entropy f the surroundings and of the system for (a) the vaporization of 1.00 mol CH₄(l) at its normal boiling point; (b) the melting of 1.00 mol C₂H₅OH(s) at its normal melting point; (c) the freezing of 1.00 mol C₂H₅OH(l) at its normal freezing point"

When solving for part (c) and using

ΔS_sys =

Is the ΔH^o_fus value negative because heat is released from a system when freezing an object?

ΔH^o_fus indicates the amount of energy it takes to melt C₂H₅OH(l). So the value would be negative since the process is reversed (freezing). E.g. A -H^o_fus is used when changing water to ice.