Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Equilibrium Reactions  and LeChatelier’s Principle or  “ I know what you did during recess”
Why? <ul><li>We have been using phenolphthalein indicator in our last two labs </li></ul><ul><li>How/why does phenolphthal...
Equilibrium <ul><li>Equilibrium Reaction : the reactants form the products at the same rate the products form the reactant...
Equilibrium is like a teeter-totter… <ul><li>Remember back to elementary school… </li></ul>Jason Claire
The Bully <ul><li>But what happens when the teeter-totter is out of balance? </li></ul>Claire Jason Sally Grrr!
Everybody’s Happy! <ul><li>How can all three kids play on the teeter-totter and be happy? </li></ul>Jason Claire Sally Thi...
LeChatelier’s Principle <ul><li>When a system at equilibrium is disturbed, the system will correct itself to restore equil...
Huh? <ul><li>An equilibrium reaction is just like our teeter-totter </li></ul><ul><li>When the kids were given a new set o...
What do you mean? <ul><li>The teeter-totter was initially at equilibrium (Jason and Claire) </li></ul><ul><li>The equilibr...
What about the Lab? Test Tube #1 <ul><li>Fe +3   +  SCN -      FeSCN +2 </li></ul>Test tube #1 was a pale orange color, w...
Test Tube #2: <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul>We added more Fe +3  ions to this tube, which causes the re...
How did Tube #2 equalize? <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul>The shift to the left causes the reaction to pr...
Test Tube #3: <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul>We added more SCN -  ions to Test Tube #3, which causes the...
How did Tube #3 equalize? <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul>The shift to the left causes the reaction to pr...
What about Test Tube #4? <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul><ul><li>How did adding Cl -  ions affect the equ...
Test Tube #4: <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul><ul><li>The addition of Cl -  ions takes some of the Fe +3 ...
How did Tube #4 equalize? <ul><li>Fe +3   +  SCN -     FeSCN +2 </li></ul><ul><li>The removal of the Fe +3  ions causes s...
The rest of the lab… <ul><li>Answer the questions for Reactions 2 and 3 on your own </li></ul><ul><li>For Reaction #3 the ...
Upcoming SlideShare
Loading in …5
×

Le chatelier’s principle

5,314 views

Published on

  • Be the first to comment

Le chatelier’s principle

  1. 1. Equilibrium Reactions and LeChatelier’s Principle or “ I know what you did during recess”
  2. 2. Why? <ul><li>We have been using phenolphthalein indicator in our last two labs </li></ul><ul><li>How/why does phenolphthalein change from pink to clear and back? </li></ul><ul><li>To understand this concept we need to learn about a couple of things… </li></ul>
  3. 3. Equilibrium <ul><li>Equilibrium Reaction : the reactants form the products at the same rate the products form the reactants </li></ul><ul><li>Two most common occurrences: </li></ul><ul><ul><li>Gases in reactions </li></ul></ul><ul><ul><li>Chemicals that dissociate in water </li></ul></ul><ul><li>Designated with a double arrow </li></ul><ul><li>reactants products </li></ul>
  4. 4. Equilibrium is like a teeter-totter… <ul><li>Remember back to elementary school… </li></ul>Jason Claire
  5. 5. The Bully <ul><li>But what happens when the teeter-totter is out of balance? </li></ul>Claire Jason Sally Grrr!
  6. 6. Everybody’s Happy! <ul><li>How can all three kids play on the teeter-totter and be happy? </li></ul>Jason Claire Sally This is fun!!
  7. 7. LeChatelier’s Principle <ul><li>When a system at equilibrium is disturbed, the system will correct itself to restore equilibrium </li></ul>
  8. 8. Huh? <ul><li>An equilibrium reaction is just like our teeter-totter </li></ul><ul><li>When the kids were given a new set of conditions, they made it work </li></ul><ul><li>When a reaction is given a new set of conditions, it will make it work, too! </li></ul>
  9. 9. What do you mean? <ul><li>The teeter-totter was initially at equilibrium (Jason and Claire) </li></ul><ul><li>The equilibrium was disturbed (Sally) </li></ul><ul><li>The system fixed itself with a new equilibrium, even though it is different from the original equilibrium (all three) </li></ul>
  10. 10. What about the Lab? Test Tube #1 <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul>Test tube #1 was a pale orange color, which was representative of an equilibrium between both sides (clear) (red) Fe +3 Fe +3 FeSCN +2 FeSCN +2 SCN - SCN -
  11. 11. Test Tube #2: <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul>We added more Fe +3 ions to this tube, which causes the reaction to shift to the left Fe +3 Fe +3 Fe +3 Fe +3 FeSCN +2 FeSCN +2 SCN - SCN -
  12. 12. How did Tube #2 equalize? <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul>The shift to the left causes the reaction to produce more of the chemicals on the right, in this case, FeSCN +2 Therefore, we see the tube turn red! FeSCN +2 FeSCN +2 Fe +3 Fe +3 FeSCN +2 FeSCN +2
  13. 13. Test Tube #3: <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul>We added more SCN - ions to Test Tube #3, which causes the equilibrim to shift to the left side. SCN - SCN - SCN - SCN -
  14. 14. How did Tube #3 equalize? <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul>The shift to the left causes the reaction to produce more of the chemicals on the right, in this case, FeSCN +2 FeSCN +2 FeSCN +2 Therefore, we see the tube turn red!
  15. 15. What about Test Tube #4? <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul><ul><li>How did adding Cl - ions affect the equilibrium of the system? </li></ul>
  16. 16. Test Tube #4: <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul><ul><li>The addition of Cl - ions takes some of the Fe +3 ions out of the equilibrium system. </li></ul><ul><li>They are more attracted to the Fe +3 since is has a bigger charge than FeSCN +2 </li></ul>
  17. 17. How did Tube #4 equalize? <ul><li>Fe +3 + SCN -  FeSCN +2 </li></ul><ul><li>The removal of the Fe +3 ions causes some of the product (FeSCN +2 ) to break apart to replace them </li></ul><ul><li>This causes the SCN- ions to increase, causing an increase in the clear color </li></ul>
  18. 18. The rest of the lab… <ul><li>Answer the questions for Reactions 2 and 3 on your own </li></ul><ul><li>For Reaction #3 the abbreviation (ppt) represents the white cloudy substance in the test tubes </li></ul><ul><li>Have fun! </li></ul>

×