1 / 6

Le Chatelier’s Principle

Le Chatelier’s Principle. When a system is in equilibrium and a stress is added to the system, the system will shift in order to alleviate itself of the stress in order to return to equilibrium Stresses: 1. concentration changes 2. temperature changes 3. pressure changes.

rea
Télécharger la présentation

Le Chatelier’s Principle

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. Le Chatelier’s Principle • When a system is in equilibrium and a stress is added to the system, the system will shift in order to alleviate itself of the stress in order to return to equilibrium • Stresses: 1. concentration changes 2. temperature changes 3. pressure changes

  2. Concentration Changes • Adding a substance shifts the equilibrium away from the added substance in order to use the excess amount up and to reestablish equilibrium A + B  C Add A, shift right (away from A) Add B, shift right (away from B) Add C, shift left (away from C) • Removing a substance shifts the equilibrium toward the substance in order to replenish the amount removed and to reestablish equilibrium A + B  C Remove A, shift left (toward A) Remove B, shift left (toward B) Remove C, shift right (toward C)

  3. Temperature Changes • Based upon whether the reaction is endothermic (takes in heat) or exothermic (gives off heat) • Follow the same rules as concentration – • Add heat, shift away from the side heat is located on • Remove heat, shift toward the side heat is located on A + B  C + heat Add heat, shift left (away) Remove heat, shift right (toward) A + B + heat  C Add heat, shift right (away) Remove heat, shift left (toward)

  4. Pressure Changes • ONLY affects GASES • Use coefficients to determine the total # of gases of products and reactants • Increase pressure, shift towards to the side with the fewest moles of gas • Decrease pressure, shift towards the side with the greatest moles of gas A(g) + B(g)  C (g) 1 mole product gas vs. 2 moles of reactant gas Increase pressure, shift right (fewest moles) Decrease pressure, shift left (greatest moles)

  5. Additional Stuff • Adding a catalyst has no affect on the equilibrium system • Adding an inert gas (gas that doesn’t react) or a gas not in the equilibrium system, has no affect on the equilibrium • The only change that will affect the value of K is a temperature change.

  6. Example N2(g) + 3H2(g)  2NH3(g) + 92 kJ/mol What affect does each of the following have on the equilibrium system? What direction will the equation shift? • Adding H2shift right • Removing NH3shift right • Decreasing volume V, P, shift right (fewest mols) • Decreasing pressure shift left (greater mols) • Increasing temperature shift left • Adding a catalyst no affect

More Related