1 / 30

II.3 Predicting Whether a Rx is Spontaneous or Not

II.3 Predicting Whether a Rx is Spontaneous or Not. p. 43 - 49. Spontaneous. a change that occurs by itself, without any help some rxs are spontaneous, others are not. Enthalpy. ∆H (heat) systems drive towards the lowest possible energy state endothermic rx = +∆H exothermic rx = -∆H.

john-mckee
Download Presentation

II.3 Predicting Whether a Rx is Spontaneous or Not

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. II.3 Predicting Whether a Rx is Spontaneous or Not • p. 43 - 49

  2. Spontaneous • a change that occurs by itself, without any help • some rxs are spontaneous, others are not

  3. Enthalpy • ∆H (heat) • systems drive towards the lowest possible energy state • endothermic rx = +∆H • exothermic rx = -∆H

  4. Entropy • ∆S • possibility for disorder, the drive towards randomness • increasing entropy = +∆S • decreasing entropy = -∆S

  5. There are 2 drives in any rx: • the tendency for a rx to go to the side with MAXIMUM RANDOMNESS (MAX. ENTROPY) • the tendency for a rx to go to the side with MINIMUM ENERGY (MIN. ENTHALPY)

  6. Ex. showing an Increase ∆S: • gas formed from a solid • gas formed from a solution • # mol of gaseous product is greater than # mol of gaseous reactant • when a solid dissolves in water

  7. Ex. of Minimum Enthalpy: PE Exo favours products Time

  8. Ex. of Minimum Enthalpy: PE PE Endo favours reactants Exo favours products Time Time

  9. The Probability of a Rx Occuring:

  10. The Probability of a Rx Occuring:

  11. The Probability of a Rx Occuring:

  12. The Probability of a Rx Occuring:

  13. The Probability of a Rx Occuring:

  14. The Probability of a Rx Occuring:

  15. The Probability of a Rx Occuring:

  16. The Probability of a Rx Occuring:

  17. The Probability of a Rx Occuring:

  18. Ex: 2NH3(g)+ 92 kJ➔N2(g) + 3H2(g) • ∆H favours___________ • ∆S favours___________ • therefore the rx ________________

  19. Ex: 2NH3(g)+ 92 kJ➔N2(g) + 3H2(g) • ∆H favours reactants • ∆S favours products • therefore the rx ________________

  20. Ex: 2NH3(g)+ 92 kJ➔N2(g) + 3H2(g) • ∆H favours reactants • ∆S favours products • therefore the rx goes to equilibrium

  21. BaCO3(s) ➔BaO(s) + CO2(g) ∆H=600kJ • ∆H favours___________ • ∆S favours___________ • therefore the rx ________________

  22. BaCO3(s) ➔BaO(s) + CO2(g) ∆H=600kJ • ∆H favours reactants • ∆S favours products • therefore the rx ________________

  23. BaCO3(s) ➔BaO(s) + CO2(g) ∆H=600kJ • ∆H favours reactants • ∆S favours products • therefore the rx goes to equilibrium

  24. 3H2(g)+ CO(g)➔CN4(g) + H2O(g)∆H = -51 kJ • ∆H favours___________ • ∆S favours___________ • therefore the rx ________________

  25. 3H2(g)+ CO(g)➔CN4(g) + H2O(g)∆H = -51 kJ • ∆H favours products • ∆S favours reactants • therefore the rx ________________

  26. 3H2(g)+ CO(g)➔CN4(g) + H2O(g)∆H = -51 kJ • ∆H favours products • ∆S favours reactants • therefore the rx goes to equilibrium

  27. H2O(l)+ heat➔ H2O(g) • ∆H favours___________ • ∆S favours___________ • therefore the rx ________________

  28. H2O(l)+ heat➔ H2O(g) • ∆H favours reactants • ∆S favours products • therefore the rx ________________

  29. H2O(l)+ heat➔ H2O(g) • ∆H favours reactants • ∆S favours products • therefore the rx goes to equilibrium

  30. Do: 14 - 16

More Related