Unsaturated, Saturated & Supersaturated Solutions Lab by 03y0NED6


									Unsaturated, Saturated & Supersaturated Solutions Lab                        Name: ______________

                                                                             Partner: ____________

Follow the procedure below and record all observations. Ignore the letters in ( ) for now.

1. Obtain a clean, unscratched test tube. Using a pipet, add 2.0 mL of water (A). Then add 0.10 g
of NaC2H3O2 (sodium acetate, which we will abbreviate SA from here on), stopper and shake for 3
seconds (B). Observation: _________________________________________________________

2. Add 4.00 more grams of SA but don’t shake yet (C). Use a permanent pen to mark the top of
the undissolved SA level on the side of the test tube. Stopper and mix for 3 sec, tilt to get any
undissolved crystals off the sides, and note any changes (D). Obs: _____________________

3. Re-mark the top of the undissolved solute level. Mix for another 5 sec and observe the changes,
including feeling the test tube (E). Obs: ____________________________________

4. Repeat step #3 until no more change occurs (F). Obs: ________________________________

5. REMOVE STOPPER! Heat test tube (by placing in hot water) for 50-60 sec. (While waiting,
weigh out another 0.10 g of SA for step #6.) Remove test tube from heat, stopper & mix for 10 sec
(G). Obs: ______________________________________________________________________

6. While still hot, add the 0.10 additional grams of SA, stopper & mix for 10 sec (H).
Obs: __________________________________________________________________________

7. Add an additional 4.00 g of SA, stopper & mix for 10 sec (I). Obs: _______________________

8. REMOVE STOPPER! Heat for 50-60 sec (while waiting, weigh out 1.00 g of SA for step #9),
then remove from heat, stopper & mix for 10 sec (J). Obs: ________________________________

9. Add the 1.00 g of SA but don’t mix (K). Cool immediately in a large cup of cool water (L).
Observe all that occurs. Obs: _______________________________________________________

10. Reheat until all crystals have dissolved (M), stopper and mix, and then cool in cold water for 50-
60 sec (N). (If recrystallization occurs during cooling, then reheat to dissolve, then recool.) Then
add 1 crystal SA and observe (O). Obs: ______________________________________________

11. Reheat until all crystals have dissolved and then an additional 30 sec (P). Stir the solution and
then wipe off the rim of the test tube with a wet paper towel to remove any crystals that may be
there. Cool in water for 50-60 sec (Q). Place a crystal in a clean weigh boat. Then, carefully, drop-
by-drop, pour your solution out onto the crystal. Observe what happens (R). Advice: Don’t allow
the growing pillar to come too close to the mouth of the test tube. (The tallest 5 pillars will receive
bonus!) Obs: _________________________________________________________________

12. Clean up your lab area and equipment, leaving it the way you found it, and place your final
product and extra solution in the sodium acetate recovery container.

1. Consider each of the points throughout the procedure indicated by the letters (A-R) and decide
whether at each particular moment, the test tube contained a solution that was unsaturated,
saturated, or supersaturated. Briefly justify your answers. The first one is done for you. (To
make sure you’re on the right track, you should have only 2 supersaturated, 5-6 saturated, and the
rest unsaturated!)

              It’s pure water…besides when some SA
              is added and shaken, it all dissolves.
A                                                          J

B                                                          K

C                                                          L

D                                                          M

E                                                          N

F                                                          O

G                                                          P

H                                                          Q

I                                                          R

2. If you were handed a solution and told to determine whether it was unsaturated, saturated, or
supersaturated, explain what you would do and what you would expect to see for each of the three
possible cases.

What would you do? ____________________________________________________________

      Unsaturated: ____________________________________________________________

      Saturated: ______________________________________________________________

      Supersaturated: __________________________________________________________

3. A solution has some undissolved crystals sitting on the bottom. Could it be…

      unsaturated?             Yes      No        Explain: ________________________________________

      saturated?               Yes      No        Explain: ________________________________________

      supersaturated?          Yes      No        Explain: ________________________________________

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