Chapter 10 - Chapter 10 Entropy and the Second Law of...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 10 Entropy and the Second Law of Thermodynamics Dr. Manuel P. Soriaga Department of Chemistry Thermodynamic Spontaneity Spontaneous : occurs without a continuous input of energy from outside the system A process that is spontaneous in one direction is non-spontaneous in the reverse direction Spontaneous does not mean instantaneous Spontaneous: Thermodynamically favored Instantaneous: Kinetically favored Needed: General criterion for spontaneity E.g.: From only thermodynamic data, how would one know if a reaction is spontaneous or not? Q: Is Enthalpy ( Δ H) the main criterion for Spontaneity? Spontaneous processes that are Exothermic: CH 4(g) + 2O 2(g) CO 2(g) + 2H 2 O (g) + 802 kJ 2Fe (s) + 3 / 2 O 2(g) Fe 2 O 3(s) + 826 kJ Spontaneous processes that are Endothermic: NH 4 NO 3(s) + 25.7 kJ NH 4 + (aq) + NO 3 (aq) N 2 O 5(s) + 109.5 kJ 2NO 2(g) + 1 / 2 O 2(g) Condition-dependent spontaneity H 2 O (l) H 2 O (s) Δ H = – 6.02 kJ (Spontaneous at T < 0°C) H 2 O (s) H 2 O (l) Δ H = + 6.02 kJ (Spontaneous at T > 0°C) A: No. Δ H is not the main criterion for Spontaneity Carnot Cycle Σ cycle (q rev /T) = 0 q rev /T must be a state function q rev /T S Entropy P V Entropy and Degree of Disorder Initial (non-equilibrium) state: Four particles and four quanta Final (equilibrium) state: Dispersal (redistribution) of energy Entropy and Degree of Disorder Initial state: Two particles. One chamber Final state: Dispersal of matter Diffusion statistics: P Two particles in one chamber = (1/2) 2 P N particles in one chamber = (1/2) N
Background image of page 1

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

View Full DocumentRight Arrow Icon
Dispersal of Matter and Dispersal of Energy Dispersal of matter leads to dispersal of energy The Boltzmann Equation As the number of microstates for a system increases, the entropy of the system increases, as
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

Chapter 10 - Chapter 10 Entropy and the Second Law of...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online