{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

07 Gibbs Free Energy - Water Ice Problem Calculate the...

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

View Full Document Right Arrow Icon
1 1 Water – Ice Problem Calculate the change in entropy of water, S system , when 2 mol of water freezes at 0 o C (273 K). For ice, H fusion = 6.01 kJ/mol S = S final – S initial = q/T A) + 44.0 J/K B) – 44.0 J/K C) + 0.022 J/K D) – 0.022 J/K 2 Water (the system) Heat flow: system (water) to surroundings (freezer) During the freezing process T water is constant (0°C) S = q/T and q = -n H fusion H fusion = 6.01 kJ/mol q H2O is negative since energy flows out of the system. q H2O = -2 x 6.01 x 10 3 J = -1.202 x 10 4 J S H2O = q H2O /T H2O = -1.202x10 4 / 273 = -44.0 J K -1
Image of page 1

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

View Full Document Right Arrow Icon
2 3 When 2 mol of water freezes, S system = - 44 J/K. The entropy decreases! Makes sense liquid solid. Water freezes spontaneously, but we said S > 0 for a spontaneous process. What gives here? Need to consider the total entropy not just the entropy of the system. 4 Total Entropy Change When water freezes, energy is transferred to the surroundings. Which means that the energy is dispersed over more states in the surroundings. So the entropy of the surroundings increases. S total = S system + S surroundings S total is also called S universe
Image of page 2
3 5 Calculate the change in entropy of the freezer (surroundings), S surroundings , when 2 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 = S final – S initial = q/T A) + 46.6 J/K B) – 46.6 J/K C) + 44.0 J/K D) – 44.0 J/K 6 Freezer (the surroundings) The freezer absorbs energy at its temp. (-15°C).
Image of page 3

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

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern