Editing revision 3 of Marg's Equilibrium Lab

ApchemWiki | RecentChanges | Preferences

Editing old revision 3. Saving this page will replace the latest revision with this text.

Notes:
Definition: If you apply a stress to an equilibrium problem, the system will try to get rid of that stress in order to go back to the original equilibrium. 
 
Mr. <nowiki>McLeod</nowiki> addition to definition: 
 
a. System can only make more reactant (run the backward reaction) or more product (run the forward reaction), nothing else. 
b. System will never get back to original equilibrium (since you add something in that has matter and energy) but comes to a new equilibrium. This is what the shift means, compare the original equilibrium material (ratio of reactant to product) compared to the new equilibrium material (ratio of reactant to product) 
 
 
 
How you answer <nowiki>LeChatlier's Principle problems for Mr. McLeod</nowiki> (see blank answer form below) 
 
1. What is stress 
2. When you are reducing stress, do you make more reactant or product (for pressure you need to indicate # of total reactant particles and product particles) 
3. Favors the forward or backward reaction (for change in temp must add endo or exo) 
4. Shift equil to the Right or Left. 
a. Shift equilibrium to the Left means that the new equilibrium position has a higher ratio of reactants to product than in the original equilibrium position. 
b. Shift equilibrium to the Right means that the new equilibrium position has a higher ratio of product to reactant than in the original equilibrium.
 
---------- 
For AP students (how actual amount of material change or is it actual concentrations of reactant to product or the ratio of reactant to product for original to new equilibrium position??): 
----- 
 
Here is a blank answer form you will fill out for each <nowiki>LeChatelier's</nowiki> Principle problem. 
 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant (fill in for pressure changes)__________________ 
 
Circle: Favoring: Forward rxn or Backward rxn: (fill in for temperature changes) _____________ 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
-------- 
Solubility Equilibria 
Write reversible reaction here. 
 
 
 
Stress: Add 12 M <nowiki>HCl</nowiki>____________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant (fill in for pressure changes)__________________ 
 
Circle: Favoring: Forward rxn or Backward rxn: (fill in for temperature changes) _____________ 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Lab observation and reason: ___________________________________________________ 
 
 Stress: Add 1.0M <nowiki>HCl</nowiki>_______________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant (fill in for pressure changes)__________________ 
 
Circle: Favoring: Forward rxn or Backward rxn: (fill in for temperature changes) _____________ 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Lab observation and reason: ___________________________________________________ 
 
 
Complex Ion Equilibria #1 
 
Write the reversible reaction for this section (include colors) 
 
 
 
Test tube 1 is control (so only has created solution in it: No stress

Test tube __2____ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Light Brown or More Red or No change 
 
Compare to lab observation: __________________________________________ 
----------------------------------
 
Test tube ___3___ 
 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Light Brown or More Red or No change 
 
Compare to lab observation: __________________________________________ 
----------------------------------
 
Test tube ___4___ 
 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Light Brown or More Red or No change 
 
Compare to lab observation: __________________________________________ 
---------------------------------
 
 
Complex Ion Equilibria #2

Write reversible reaction here:
 
 
For this reaction you need to know a few more pieces of information. 
 
1)<nowiki>HCl</nowiki> --> H+ (or H3O+) + Cl1- 
So, in a bucket of <nowiki>HCl</nowiki> solution, there is no <nowiki>HCl</nowiki> but only H+ and Cl1- ions. 
Therefore, adding <nowiki>HCl</nowiki> really means adding H+ (or H3O+) 
 
2) <nowiki>NaOH</nowiki> ---> Na1+ + OH1- 
Then the OH1- + H+ ---> H2O

Looking at the above two equation, one needs to realize that you can explain lab observations in two different ways with respect to <nowiki>LeChatlier's Principle</nowiki>.

2a) OH1- from the <nowiki>NaOH</nowiki> consumes H+ as in the above reaction so adding the chemical is actually a decrease in [H+] or

2b)OH1- from the <nowiki>NaOH</nowiki> reacts with H+ to form H2O so adding the chemical is actually increase [H2O]. 
 
 
So, for the reactions with <nowiki>NaOH</nowiki> below, please alternate explanation (once using 2a & another times using 2b). 
 
 
-------------------------------
 
Test tube ___5 (HCl added)___ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
---------------------------------
 
 
Test tube _6 (HCl added)_____ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
---------------------------------
 
 
Test tube ___6 <nowiki>(NaOH added)</nowiki>___ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
---------------------------------
 
 
Test tube __7 (<nowiki>NaOH added)</nowiki>____ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
---------------------------------
 
 
Test tube __8 (<nowiki>NaOH</nowiki> added)____ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
 
Test tube __8 (<nowiki>HCl added</nowiki>)_____ 
Stress: _______________________________________________________________ 
 
How rxn tries to remove stress: _________________________________________________ 
 
Circle: Make more product or more reactant 
 
Circle: Favoring: Forward rxn or Backward rxn 
 
Circle: Shift Equilibrium to: Left(more reactant) or Right (more product) 
 
Solution turned: More Yellow or More Orange or No change 
 
Compare to lab observation: __________________________________________ 
 
 
Acid Base Equilibria 
 
Write reversible reaction here: 
 
 
Test tube 1 is control (so only has created solution in it: No stress

View other revisions
ApchemWiki | RecentChanges | Preferences