Aluminum
and Copper (II) Chloride Lab
Purpose: By
reacting aluminum with copper (II) chloride, you will make a reaction.
If you know the grams of aluminum to be
reacted you should be able to predict how many grams of a “brown substance” will
be produced by using a process known as stoichiometry.
Pre-Lab: Make 15 mL of a 9.92 x 10-1 M
solution of Copper (II) Chloride in water.
On your data table, record the GRAMS of Copper (II) Chloride
you will need to add to the
15
mL of water. Put your solution in your
small beaker
Procedure:
1. Obtain a length of aluminum wire from your
teacher. Then, coil it up into a loose
coil with a little left over as a “handle”.
See drawing on front board
2. Find the mass of your
Al wire and record on your
data table.
3. Find the mass of your
small beaker and record it on
your data table.
4. Make the solution of Copper (II) chloride as
specified in the pre-lab
5. Dip the coil into the Copper (II) Chloride
solution and allow it to collect copper for about 1 minute. BE CAREFUL NOT TO BREATHE THE FUMES PRODUCED
The wire will be coated with a brown substance (what is that substance? What is the gas produced?)
6. Using your water bottle, squirt a strong
stream of water on the coil to remove the brown substance so it falls into the
beaker. You want the brown substance to
fall into the beaker! WEAR YOUR GOGGLES
TO AVOID SPLASHING INTO YOUR EYES. If
you cannot get all of the brown substance off of the wire, you might try putting
on a rubber glove and “squeezing” the substance off into the beaker. DON’T use your bare hands since the
chemicals are poisonous.
7. Dry the Al coil with a paper towel and
reweigh it. Record the mass after the reaction on your data
table.
8 Decant the blue liquid from your small
beaker down the drain. BE CAREFUL NOT
TO LET ANY OF THE BROWN SUBSTANCE GO DOWN THE DRAIN.
9. Squirt some water (about 20-30 mL) from your
water bottle into your beaker to clean the brown substance. Decant this also into the sink. AGAIN, BE CAREFUL NOT TO LET ANY OF THE
BROWN SOLID GO DOWN THE SINK.
10. Put your beaker on one of the hot plates in
the fume hood and let it dry out.
11. While your beaker is “drying”, answer the questions posed to you in the
question section. Do not copy the
questions, but show all work!
12. WHEN THE BEAKER IS COOL, reweigh it and record its mass on the
data table.
13. Determine the mass of the
brown substance in the beaker and record
this on your data table.
Data Table:
Mass of Al wire
_________g
Mass of empty small beaker
_________g
Grams of Copper (II) Chloride to be added to 15 mL of water ________g
Mass of Al wire after it was dipped in Copper (II) Chloride solution ________g
Mass of Beaker & Brown Substance after heating/drying/cooling _______g
Mass of brown substance by itself ___________g (this is the actual mass of the copper after drying)
Predicted
mass of brown substance _______g (from question #8)
Questions:
1. Write out a balanced equation for this
reaction.
2. Is this reaction: Combustion, Single
replacement, Double replacement, Synthesis or Decomposition?
3. By looking at your balanced equation and the
Coefficients in that equation, how
many Aluminum moles are on the Reactant side of the equation?
4. By looking at the balanced equation, how
many Copper moles on the Product side of the reaction?
5. Determine how many moles of Aluminum
were used in this reaction. To do this,
subtract the mass of the Aluminum wire AFTER
the reaction from the mass of the original Aluminum wire. Then, convert the grams of aluminum wire used up in this reaction into moles of aluminum.
6. Divide your answer to number 5 by the number
of moles of Aluminum you have on the reactant side. (see your answer to #3)
7. Multiply your answer to number 6 by the
number of moles of copper you have on the product side. (see your answer to #4)
8. Your answer to number 7 is the number of moles of copper you should expect to
create in this experiment. Convert the
answer to question #7 to grams of
copper and you should have the amount of copper that will come out of this
experiment.
9. Subtract your answer from #8 from the grams
of “brown substance” you got to see how far off you were.
10. Find the percentage error of your results by
using the following formula:
Percentage
error = êPredicted grams of brown sub. - Actual grams of
brown sub.ê x100
Predicted
grams of brown sub.