Arnoldi
Honors Chemistry
Bonding
The Eight Solution Problem
When two substances are put together they can do two things: combine physically and make a mixture, or combine chemically to form new substances. Indicators of these chemical changes include many bubbling, heat / light evolving, precipitates forming, and color changing. In this experiment, you will observe these changes. You will then identify the same eight substances when they are supplied as unknown solutions.
MATERIALS Distilled Water Toothpicks
Eight Known Solutions Q-tips
Eight Unknown Solutions 96 Well Microplate (2)
Solutions to be tested:
Copper (II) Nitrate Silver Nitrate
Iron (III) Nitrate Sodium Carbonate
Lead (II) Nitrate Sodium Iodide
Nitric Acid Sodium Hydroxide
PROCEDURE
Known Solutions
1. Each box on the data table (that does not have an X in it) represents the intersection of two solutions. For example, the second column, second box down is HNO3 and AgNO3. For every box on the data table (that does not have an X in it) put in 3 drops of each of the solutions. Be careful not to put in more than 3 drops, the well will overflow!
2. Use a toothpick to stir the contents of each well. Make sure you clean the tooth pick when moving from well to well!
3. Examine each well for any observable changes in the solutions. Record your results in the KNOWN data table.
4. Discard the solutions in the sink. Clean the microplate with water and 1 Q-tip. Rinse the sink with lots of water.
Unknown Solutions
Follow the same directions as for the known solutions, but substitute unknown solutions A through H for the known solutions.
Known Table
HNO3 / / / / / /
AgNO3 /
NaOH /
Pb(NO3)2 / /
Fe(NO3)2
Cu(NO3)2 / /
Na2CO3
NaI /
Unknown Table
A / / / / /
B /
C /
D / /
E
F / /
G
H /
LEFT BLANK ON PURPOSE
Arnoldi
Honors Chemistry
Bonding
The Eight Solution Problem
DATA
Known Table
/ HNO3 / AgNO3 / NaOH / Pb(NO3)2 / Fe(NO3)2 / Cu(NO3)2 / Na2CO3 / NaIHNO3 / / / / / /
AgNO3 /
NaOH /
Pb(NO3)2 / /
Fe(NO3)2
Cu(NO3)2 / /
Na2CO3
NaI /
Unknown Table
A / / / / /
B /
C /
D / /
E
F / /
G
H /
ANALYSIS
1. Theory and Discussion
Think back to earlier chapters… what have we learned in class that was demonstrated in this laboratory? Use the opening paragraph to the lab as a clue.
2. Compare Your Known and Unknown Observations
Find one specific observation that clearly occurred in both the KNOWN and UNKNOWN tables and fill in the blanks below…
Known ______and Known ______showed
______when they combined.
Unknown ______and Unknown ______also showed this observation.
Therefore I can deduce that Unknown ______and Unknown ______must
be Known ______and Known ______, although I don’t know yet which is which.
3. Repeat the above process until you can identify all of the unknowns.
4. Identify the Unknowns
A = ______
B = ______
C = ______
D = ______
E = ______
F = ______
G = ______
H = ______
5. Error Analysis
What could go wrong to lead you to incorrect identification of your unknowns?
CONCLUSION
List two specific changes that occurred in this laboratory that indicated a chemical reaction occurred. Pick two that represent the most common type(s) of indicator observed.