Eight Solution Problem Lab
In this lab, you will use your powers of observation to identify eight unknown solutions.
Your task: On Day 1, you will be given eight labeled solutions. These solutions are:
Nitric acid, HNO3
Lead(II) nitrate, Pb(NO3)2
Sodium hydroxide, NaOH
Silver nitrate, AgNO3
Potassium Iodide, KI
Sodium carbonate, Na2CO3 Iron(III) nitrate, Fe(NO3)3
Copper(II) nitrate, Cu(NO3)2
You will combine each solution with every other solution and make careful notes about
what results.
On Day 2, you will be given the same eight solutions. However, they will only be labeled
with a letter. You will again combine each unknown solution with every other solution
and use your observations to determine the identity of each solution.
To conserve chemicals, you will use conduct a “microscale” lab. Each lab table will be
given eight dropper bottles or test tubes with pipettes to share. You will combine only
two drops of the chemical on plastic wrap.
All the test tubes will have the same pipettes so it is absolutely imperative to remove
only one pipette at a time and make absolutely certain that none of the pipettes are mixed
up. You must also ensure that you do not touch the pipette to the plastic or any solutions
already on the plastic wrap.
Pre-Lab Requirements:
To keep you from getting confused about which drops are which on the plastic wrap, you
will create a guide sheet to go underneath the plastic wrap. Draw 28 circles (about the
size of a quarter) on a sheet of paper (one for each combination of chemicals) and label
each circle with what chemicals should be combined in it. Create a second guide sheet
for Day 2 using the letters A, B, C etc. for the unknowns. Also create a data sheet where
you can record your observations about each combination. It may be helpful to you to
make your data sheet look like your guide sheet.
In Lab:
1. Tape your guide sheet to the table. Tape the plastic wrap over your guide sheet. Use
the circles to aim your drops.
2. Carefully combine each chemical with only one other chemical at a time by adding two
drops of each solution to the sheet. Diligently record observations about each
combination. Be careful not to contaminate the pipettes by touching them to other
chemicals.
3. When finished, carefully ball up the plastic wrap and place it in the trash.
Lab Report:
Include the following things in addition to all required elements on the Lab Report
Instruction Sheet:
A) Purpose
B) Analysis questions:
1) What is the identity of each unknown solution (i.e. Unknown A is ____, B
is _____, etc.)?
2) Describe in detail the process you used to identify the unknown solutions.
It may be helpful to use the first unknowns you figured out to illustrate
this process. You should have information about how you figured out
each of the eight unknowns or you will lose significant points.
3) What effect would poor observation skills during the lab have on your
analysis?
4) How might these observation techniques be used in the real world? Be
creative. There should never be unlabeled bottles of solutions in real labs,
so this should not be your answer.
C) Conclusions
D) Original Data Sheet (points will be deducted from your lab if this is not included)