Chemical Equilibrium
***The lab instructor will NOT tell you which problems you got incorrect on
your pre-lab assignment!! They will simply tell you there are errors and will
not stamp the assignment (why might you ask?? Because the answers are
opposites! If they tell you your increase was incorrect, well then I guess the
answer was supposed to be decrease! No thinking involved there!)
Start with ~35 drops of zinc nitrate instead of 25 drops!!!
For each section: think about the species involved. Think about
what adding a species does to the equilibrium of the reaction, think
about any “side” reactions that are given. How does a side reaction
affect the concentration of the species involved? Would the
concentration of that species be increasing? If so, how would that
affect the equilibrium? Is the concentration of that species
decreasing? If so, how would that affect the equilibrium?
Page 3: make sure to add 4 drops of HCl (maybe 5 if need be).
Page 3: make sure to add 2 drops of NaOH
Page 4: make sure to add those 5-6 more drops of NaOH
Be careful and observant when adding HCl!!
The results (and your answers!) depend on your observation and
technique. THINK about what you expect would happen to the
equilibrium before you add a species.
Then see if your
thoughts/hypotheses are confirmed. If they are not, see the lab
instructor then to discuss your ideas, your thinking so we can help
you understand equilibrium because. . . (see below!)
For each section, it is in your best interest to leave out the chemicals
and check with the lab instructor before moving on to the next
section. Since the answers are usually opposite of one another, you
will not be told which answers in your lab are incorrect! It’s not
very helpful nor does it involve much thinking if you write increase
and we tell you it’s wrong – you can simply change your answer to
decrease and away you go. We want you to think and understand
equilibrium! Do not be surprised if your lab instructor gives you a
partial or final stamp and tells you that some of your equilibrium
answers are not correct. And do not be surprised when they tell you
that they will not identify which ones. A lot of these questions could
be answered without actually doing the lab and just thinking about
how adding a species will affect equilibrium. Doing the experiment
will provide visual observational proof (hopefully!!) of your
expectations!