Question

41. Given the values of AH.. Si, and T. determine AS predict whether each reaction #33 Calculate Change in entropy that occurs in the system When 45.0g of acetone (C3 A60) freezes at its melting point (34.617 2 Chem formula (C₂H₂O) melting pt (-94.8%) Ateur (5. 69 XJ/md). Change Change in entropy of the universe Asund - Assys + 2 sur •

Answer 1

We have to calculate entropy change of system in given phase transformation.

as given -

weight of acetone = 45 gm

melting point = —94.8⁰ C = ( 273 -94.8 ) K = 178.2 K

molar mass of acetone = 58 gm mol^—1

moles of acetone = 45 gm / 58 gm mol^—1 = 0.78 mol

$\Delta$H_fusion = —$\Delta$H_{freezing =} 5.69 KJ / mol

$\Delta$H_freezing For 45 gm acetone = — ( 5.69 KJ / mol ) x 0.78 mol = —4.438 KJ = —4438 J

$\Delta$S_freezing = $\Delta$ H_freezing / T_fus = —4438 J / 178.2 K = —24.9 J / K

so change in entropy of system = —24.9 J / K