Question

The heat of fusion of dichloromethane is . Calculate the change in entropy when of dichloromethane freezes at . Be sure your answer contains a unit symbol. Round your answer to significant digits.

Answer 1

This is an incomplete question, here is a complete question.

The heat of fusion $\Delta H_f$ of dichloromethane (CH₂Cl₂) is 6.2 kJ/mol. Calculate the change in entropy ΔS when 345. g of dichloromethane freezes at -95.1 degree C. Be sure your answer contains a unit symbol and the correct number of significant digits.

Answer : The value of change in entropy is 35 J/mol.K

Explanation :

Formula used :

$\Delta S=\frac{\Delta H_{fus}}{T_f}$

where,

$\Delta S$ = change in entropy  = ?

$\Delta H_{fus}$ = change in enthalpy of fusion = 6.2 kJ/mol

$T_f$ = fusion temperature = $-95.1^oC=273+(-95.1)=177.9K$

Now put all the given values in the above formula, we get:

$\Delta S=\frac{\Delta H_{fus}}{T_m}$

$\Delta S=\frac{6.2kJ/mol}{177.9K}$

$\Delta S=\frac{6.2\times 10^3J/mol}{177.9K}$

$\Delta S=34.85J/mol.K\approx 35J/mol.K$

Therefore, the value of change in entropy is 35 J/mol.K