Quantitative Chemical Analysis
Yoda wisdom #47: No! Try not. Do…or do not. There is no try.
Objectives
 Determine the number of moles of iron
consumed and copper
produced in the reaction of iron with
aqueous copper (II)
chloride.
 Determine the most
likely ion of iron
formed in the lab
Background Information
In this experiment, you will carry out a chemical reaction and determine what ion
of iron forms in a particular chemical reaction.
As an example, suppose we reacted lithium metal with aqueous magnesium chloride. Lithium can only form one ion, Li+. Therefore there is only one possible reaction that can take place:
2 Li(s) + MgCl2(aq)  2 LiCl(aq) + 2 Mg(s)
BUT, what if the solid metal added to the aqueous solution was a transition metal
and could form MORE THAN one type of ion (hmm...where on the periodic table
would we find these types of element)? If this is the case, there is more than one
type of reaction that could happen. The question is, what reaction DOES happen
(and therefore which ion forms)? That is what we are going to determine in this
lab.
Specifically, you will allow iron metal to react with a solution of copper(II) chloride to produce copper metal and an iron compound. You will measure the mass of
the iron used and the copper formed in the reaction. Using these mass measurements, you will determine the number of moles of iron and copper involved in the
reaction.
The ratio of moles of iron consumed to moles of copper produced will be used to
determine what ion of iron formed during the reaction.
Equipment
safety goggles
1 50-mL graduated cylinder
2 250-mL beakers
1 plastic wash bottle
1 glass stirring rod
1 drying oven/class
1 crucible tongs
balances
1 glass-marking pencil/class
Materials
iron nails, Fe
copper (II) chloride, CuCl2
1 M hydrochloric acid, HCl
steel wool
paper towel
sodium bicarbonate, NaHCO3
deionized water
Preparation
Read the entire lab procedure. Then, referring back to the procedure, create a data table(s) to record all of the
necessary data (look for key word such as weigh, record, observe, etc.)
This will be checked off before you start the lab. In addition, it would be helpful to look at the questions you
will be expected to answer before you begin the lab.
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Procedure
As you perform the experiment, record your data in your data table(s).
Day 1
1) Label a clean, dry 250-mL beaker by writing your names on a piece of labeling tape with a permanent
marker. Weigh the beaker to the nearest 0.01 g. Record this mass.
2) Add 7.5 g of copper (II) chloride, CuCl2, powder to a 250-mL beaker.
3) Add 50 mL of deionized water (in the blue squirt bottles) to the copper II chloride crystals in the 250-mL
beaker. Stir the mixture until the crystals are completely dissolved. Record your observations.
4) Clean four dry iron nails with steel wool to remove any rust or protective coating. Place the nails on the
balance pan and determine their combined mass to the nearest 0.01 g. Record this mass.
5) Slide the nails carefully into the solution of copper (II) chloride. Record any evidence of a chemical reaction. Place the beaker in a safe place (side of the room or in the hood) and let the reaction proceed overnight.
Day 2
6) Using a pair of clean crucible tongs (being very careful) remove
any nails that may be left from the solution. Hold each nail over
the beaker and use a jet of water from a blue wash bottle to rinse
the product off the nail into the beaker. (See Figure 1)
7) DO NOT THROW THE NAILS OUT!!! Allow the nails to airdry in a safe place. (You will need to weigh them later.) Be sure
to keep track of which nails are yours.
8) Carefully pour the liquid portion of the mixture into a separate container (another 250-mL beaker will do), leaving
the solid in the original beaker. (See Figure 2) This process is called decanting. Dispose the liquid solution by
pouring it into the sink. Be sure not to throw any of the
solid in the sink. You will need this to weigh later.
Rinse the collection beaker with water.
Figure 1
9) Wash the solid product in the beaker with 25 mL of distilled water from the blue squirt bottles. Pour off the liquid
Figure 2
into the separate container. If the solid product should accidentally fall into the separate container, pour the product
back into the first beaker. Repeat the washing and decanting procedures another three times, being careful
to avoid any loss of the solid. The liquid can be safely poured into the sink.
10) Now, wash the remaining solid product with 25 mL of 1 M HCl. CAUTION: HCl is an irritant at this concentration. Avoid skin contact. Wash the acid into a beaker and neutralize it with sodium bicarbonate (baking soda) before pouring it into the sink for disposal. Wash the solid again for the fifth time with 25 mL of
distilled water from the blue squirt bottle. You can pour this liquid directly into the sink.
11) Place the beaker containing the solid product in the drying oven.
12) Weigh the dry nails together to the nearest 0.01 g. Record the mass in your data table. Allow the beaker
with the solid in it to dry overnight.
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Day 3
13) After the solid product is dry and the beaker has cooled, weigh the beaker and its contents to the nearest
0.01 g. Record this mass in your data table. When you are finished, place the nails in the beaker labeled
“nails” in the back of the room and put the solid product in the garbage can.
Analysis
1) Determine the mass of iron lost by the nails.
2) Determine the number of moles of iron used. (See Introduction.)
3) Determine the mass of the product produced.
4) Assuming that the product is copper metal, determine the number of moles of copper produced. Remember,
Iron can be a +2 or a +3 charge, it is up to you to tell me which one it is (See Introduction.)
5) Calculate the mole ratio of iron used to copper produced. Express this ratio as a simple whole number ratio.
(Round if necessary, don’t forget your units!!) It should look like:
Moles of iron used
_____________________
Moles of copper produced
Results and Conclusions
Iron can form two types of ions: Fe+3 and Fe+2. The two possible equations for this reaction are as follows:
For the Fe+3
____ Fe + ____CuCl2
____FeCl3 + ____Cu
For the Fe +2
____Fe + ____CuCl2
____FeCl2 + ____Cu
1) Balance the above equations.
2) What are the two mole ratios that are formed in the two equations? Remember, for your ratio, you want the
moles of iron used:moles of copper produced
3) What was the ratio of moles of iron used: moles of copper produced in your lab?
2) Referring to the ratios from the two equations above and your mole ratio from number 3, which ion of iron
formed in this reaction?
3) Explain how you chose the ion of iron that formed. Be sure to refer to your equations and mole ratios.
4) What type of reaction occurred in this lab? Explain how you know this.
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