Question

the heat of fusion of acetone is 5.7 kJ/mol. Calculate to two significant figures the entropy change when 6.3 mol of acetone melts at its melting point of -94.7C at constant pressure

Answer 1

Answer: The entropy change of the process is
`2.0* 10^2J/K`

Step-by-step explanation:

To calculate the entropy change for different phase at same temperature, we use the equation:

`\Delta S=n* (\Delta H_(f))/(T)`

where,

`\Delta S` = Entropy change

n = moles of acetone = 6.3 moles

`\Delta H_(f)` = enthalpy of fusion = 5.7 kJ/mol = 5700 J/mol (Conversion factor: 1 kJ = 1000 J)

T = temperature of the system =
`-94.7^oC=[273-94.7]=178.3K`

Putting values in above equation, we get:

`\Delta S=(6.3mol* 5700J/mol)/(178.3K)\\\\\Delta S=201.4J/K=2.0* 10^2J/K`

Hence, the entropy change of the process is
`2.0* 10^2J/K`