Introduction to Chemical Equations and Reactions
Date_____
Purpose: This lab will help you to see the quantitative relationship between reactants and products in a
chemical reaction, and justify the equation that is written to describe the reaction. In this case elemental iron
will be placed into a solution of copper(II) chloride. When ionic compounds dissolve in water, the cations
and anions (here, Cu+2 and Cl-1) dissolve and move apart, becoming free to interact separately with other
atoms or ions in the solution. In this experiment Cu+2 ions and Cl-1 ions will interact with neutral iron atoms.
Examine the two equations below. Notice the symbols, (s) and (aq), used to indicate the physical states of the
reactants and products. Also notice the iron compounds that are produced. They are different because iron can
form two different ions, depending on how many electrons it loses: Fe+2 or Fe +3. At this point you really
don’t know which one is “right”. Balance each equation with whole-number coefficients to prove
Conservation of Matter. Careful measurements and evaluation of data will enable you to decide what the
actual outcome is.
a)
___Fe(s) + ___ CuCl2(aq) ---> ___ FeCl2(aq) + ___ Cu(s)
b)
___ Fe(s) + ___CuCl2(aq) ---> ___ FeCl3(aq) +___Cu(s)
Overview: Place two clean iron nails into a solution of copper(II) chloride. When the reaction is complete,
obtain the mass of the iron that remains and collect the new copper that has formed. Since moles of
substances are simply multiples of individual atoms and ions, we will examine the mole amount of irons that
reacts and the mole amount of copper that is produced to determine how they “fit together” in the reaction.
Procedure:
 Obtain the mass of a clean, and dry beaker – with a label on it. The 150 ml or 250 ml size works best.
 Add approximately 4.00 grams of CuCl2 to the beaker. (Use plastic spoon, not a metal scoopula.)
 Add approximately 25 – 30 ml of deionized water to the beaker – stir the CuCl2 solution with a glass
rod until it is mixed completely.
 Clean the surfaces of two iron nails thoroughly with steel wool.
 Obtain the mass of the clean nails and then place them into the CuCl2 solution.
 After 30 – 40 minutes, remove the nails with tongs. Use a wash bottle with deionized (‘DI’) water to
rinse loose solid material back into the beaker. Allow the nails to dry before obtaining their mass.
 Decant (carefully pour off) the blue-green liquid into a waste beaker. Reserve the entire solid product
in the original beaker. Use a stirring rod to block spillage of the solid product when decanting.
 Rinse the copper with DI water – decant the liquid as before. Repeat the process several times, until
the water you are decanting is clear.
 Rinse the copper with approximately 15 ml of HCl solution.
 Decant and wash again with DI water.
 Place the beaker into the oven – obtain the mass when the contents are dry.
 Transfer the dry copper to a location as directed by the teacher.
Data:
Mass of empty beaker
Mass of beaker plus CuCl2
____ g
____ g
Initial mass of iron nails
Mass of iron nails left over
____ g
____ g
For mole calculations:
Molar mass of iron
____g/mole
(note: the leftover iron never reacted)
Mass of beaker plus dry copper
____ g
Molar mass of copper ____g/mole
Analysis: Complete the following calculations. Read each prompt carefully and apply it to your procedure.
Show the work neatly, even if the “math” seems trivial. Be sure to apply unit labels to all factors and answers.
Mass of iron that reacted
____ g
Moles of iron that reacted: ______ moles
(remember: not all of the iron you started
with reacted… we are only interested in what reacted.)
Mass of copper produced
____ g
Moles of copper produced: ______ moles
(note: this is called the “actual yield”
because it was obtained from actual labwork)
Express a simple mole ratio from your own data: moles of copper produced/moles of iron reacted _____
For each of the equations you completed on the front of this lab sheet, examine the coefficients The
coefficients tell you the simplest ratio of ATOMS that fit together. But a “MOLE” is simply a large batch
of atoms, so the coefficients will also tell you the ratio of MOLES that react.
Use the balanced equation coefficients here:
Equation that produces Fe+2 ions:
Cu produced:Fe used = moles of copper
Equation that produces Fe+3 ions: Cu produced:Fe used = moles of copper
moles of iron
moles of iron
= ______
= ______
Which one of these ratios fits best with your own experimental ratio of moles, calculated from lab
data? Re-write that balanced equation below:
_________________________________________________________
Interpret the numbers from the equation you re-wrote above:
For every ___atom(s) of iron in the reaction, ___ ion(s) of Cu+2 will react, producing
___ atom(s) of Cu plus ____ ion(s) of Fe +? .
AND,
For every ___mole or mole-part of iron in the reaction, ___ mole or mole-part of Cu+2 will
react, producing ___ mole or mole-part of Cu plus ____ mole or mole-part of Fe +?
Conclusion: Answer the following questions using complete sentences. Provide specific details that support
your answers.
1. What appears to be the relationship between the moles of iron used up and the moles of copper produced in
your reaction? Explain how your data proves this. This was the purpose of the experiment…
2) Considering the data you obtained and the calculations you performed, which one of the two equations at
the beginning of the lab is the one that fits your experimental results? Explain how you make this decision.
This is based on the results of your analysis above…
3) What procedural steps are likely to have the greatest impact on the accuracy of the results in kind of
experiment? Be specific.
4) Extend the concept to make a prediction: How many moles of copper would be produced if 2.5 grams of
iron were reacted completely as shown in this experiment? What would the mass of that copper be?