Lec5 - Problem from Last Time Calculate the change in...

This preview shows pages 1–4. Sign up to view the full content.

1 1 Calculate the change in entropy of the freezer (surroundings), S surroundings , when 0.444 mol of water freezes at 0 o C (273 K). The temperature of the freezer is –15 o C (258 K) For ice, H fusion = 6.01 kJ/mol S = q/T A) + 10.3 J/K B) + 23.3 J/K C) + 9.77 J/K D) + 22.0 J/K Problem from Last Time 2 Freezer (the surroundings) S freezer = q freezer /T freezer The freezer absorbs energy at its temperature. (258 K) so q freezer > 0. q freezer = q water S freezer = q freezer /T freezer = (+0.444 mol x 6010 J/mol)/258 K = +10.3 J/K

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 3 The Universe (total) S universe = S water + S freezer S universe = 9.8 J/K + 10.3 J/K = + 0.5 J/K So the total entropy change is positive, the total entropy increases, and water freezes spontaneously at 0 0 C because energy is transferred to surroundings at a lower temperature. T q S 4 Gibbs Free Energy S universe = S surroundings + S system J Willard Gibbs, a Yale professor regarded as the father of Thermodynamics, wanted to express these ideas in terms of the system only! So he rearranged equations and invented a new concept that is named after him. 1839 - 1903
3 5 S universe = S surroundings + S system S surroundings = q surroundings /T = H system / T S universe = H system / T + S system Multiply through by T to obtain  S universe = H system T S system How did he do this??? 6  S universe = H system -T S system Right-hand side only depends on the system. So Gibbs define a new function

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 11

Lec5 - Problem from Last Time Calculate the change in...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online