Name:__________________________
Double Replacement Lab
Reminder – Goggles must be worn at all times in the lab!
PRE-LAB DISCUSSION:
A PRECIPITATE is an insoluble substance formed by the reaction between chemicals in solution. A list
of reactions will be given to you. The reactants are on the left side of the equation, and the products are
on the right. The precipitate will be found on the product side. Keep in mind that an equation gives a
condensed picture of what happens when two chemicals react.
PURPOSE:
The purpose of the lab is to observe semi-micro scale precipitation reactions, and to use a solubility
table to identify the insoluble product, when there is one.
PROCEDURE:
Predict the products and balance the following double replacement reactions. Then, identify the
precipitates using the table on page 2. You may want to do your work step on a scratch piece of
paper and attach to lab later.
Double Replacement Reactions
A.
NaCl
+
AgNO3

B.
KI
+
AgNO3

C.
NaOH
+
AgNO3

D.
Na3PO4 +
AgNO3

E.
NaCl
+
Pb(NO3)2

F.
KI
+
Pb(NO3)2

G.
NaOH
+
Pb(NO3)2

H.
Na3PO4 +
Pb(NO3)2

I.
NaCl
+
CuSO4

J.
KI
+
CuSO4

K.
NaOH
+
CuSO4

L.
Na3PO4 +
CuSO4

Precipitates
(if any)
Identifying the precipitates
Use the solubility table on the right to
identify the precipitate (the insoluble
substance) in each reaction.
Performing Drop Reactions
1. Get a well plate and be sure that they are clean and dry.
2. Above is a list of 12 reactions. For each reaction, drop 3-5 drops of the first reactant in a depression on the
spot plate, and then place 3-5 drops of the second reactant in the same depression. Be careful not to touch the
dropper bottle tip to the reactant mixture.
3. Perform drop reactions for each of the following chemical reactions. Be sure to record your observations
below in the table of any precipitates. After each reaction, write “ppt” if a precipitate formed and “NR” if there
was no reaction.
NaCl
AgNO3
Pb(NO3)2
CuSO4
KI
NaOH
Na3PO4
Follow-up questions:
1. How can two clear solutions mix and produce a cloudy precipitate -- what is going on?
2. For the mixtures you considered NR (no reaction). Is it possible a reaction is happening?
Explain.
3. Some of your precipitates had a very distinct color. Which ones were they, and what was its
color?