Analysis
These results show the types of reactions for each and what the products are.
For the first experiment, it is clear that the piece of iron turned into copper from
the color change, clearly proving a single replacement reaction occurred. For the
second experiment, there is a yellow precipitate that forms (but not the entire
thing), proving that a double replacement reaction took place. For the third
experiment, the crackle sound is a clear indicator that hydrogen was a product,
also proving a single replacement reaction occurred. For the fourth experiment,
the fact that the glowing splint continued to burn was a clear indication that
oxygen was a product, proving that a decomposition reaction took place. For the
fifth experiment, the fact that the flame is smothered clearly shows that no
oxygen is being released (instead it is carbon dioxide). This also shows that a
decomposition reaction occurred. For the fifth reaction, the fact that the entire
thing burned up into water and carbon dioxide, obviously proves that a
combustion reaction happened.
Analysis Questions
1. Classify each of the observed reactions as one of the 5 reaction
types. Record your answers in Data Table 1.
See Above
2. Write an equation for each reaction observed. Indicate the state (s, l,
g, aq) for each reactant and product, then balance each equation.
Fe (s) + CuSO4 (aq)  Cu (s) + FeSO4
Pb(NO3)2 (aq) + 2KI (aq)  PbI2 (aq) + 2K(NO3) (s)
Mg (s) + HCl (aq)  H2 (g) + MgCl2 (aq)
2H2O2 (l)  2H2O (l) + O2 (g)
2NaHCO3 (aq)  Na2CO3 (aq) + H2O (g) + CO2 (g)
CH3CH2OH (l) + 3O2 (g)  2CO2 (g) + 3H2O (g)
3. Although no combustion reactions were described in the Procedure
section, two combustion reactions did occur in the course of this
experiment. The reactants were H2 and CH4 (natural gas),
respectively. Write a balanced equation for the combustion of each
of these substances.
2H2 + O2  2H2O
CH4 + 2O2  2H2O + CO2
4. Identify the combustion reaction in the previous question that is also
a combination reaction.
The first combustion reaction (involving H2) is also a combination reaction
because 2 solitary elements are becoming 1 compound. In the other equation,
there is a compound and an element combing to form 2 different compounds,
which is not a characteristic of a synthesis (or combination) reaction.
5. Describe in your own words the five types of chemical reactions.
Explain how to distinguish each of these types of reactions.
Synthesis Reaction – A reaction in which multiple (2 or more) elements combine
to form one compound. A + B could become AB.
Decomposition Reaction – A reaction where one compound splits into multiple (2
or more) elements. Compound AB could split into A + B.
Single Replacement Reaction – A reaction where and element swaps with
another element in a compound. If there is element A and compound BC, then
the products would be B and AC. This only is true if A is a more reactant element
than B.
Double Replacement Reaction – A reaction where 2 compounds swap their
elements. If compound one is made of AB and compound 2 is made of CD, then
the products would be AD and BC. At least one of the products has to be a gas
(HS, HSO3, or HCO3), water, or a precipitate (not soluble in water).
Combustion Reaction – A reaction where an element containing o and H and/or
C that reacts with O2 to form H2O and/or CO2.
6. List the tests that were used to identify the three gases produced in
this experiment.
The tests performed to test the three gases produced were holding a burning
splint over the test tube, putting a burning splint in the tube, and holding a
glowing splint over a test tube. When a flaming splint was put over the test tube
in the Mg + Cl reaction, the flame popped/crackled, which showed that H2 was
formed. When a glowing splint was put over the gas given off by the H2O2 + heat
reaction, the glow continued to burn the rest of the wood splint, proving that O 2
was released. When a flaming splint was put in the test tube for the NaCO3 +
heat reaction, the flame was smothered, proving that no O 2 was given off, but
instead CO2 was.
7. Which type(s) of reactions are characterized by:
a. Two products
Decomposition reaction, Single Replacement Reaction, Double Replacement
Reaction, sometimes Combustion Reaction
b. A single reactant
Decomposition Reaction
c. Two reactants
Synthesis (or Combination) Reaction, Single Replacement Reaction, Double
Displacement Reaction, Combustion Reaction
d. A single product
Synthesis (or Combination) Reaction, sometimes Combustion Reaction
8. Develop a Hypothesis – Based on the results of this lab, develop a
hypothesis about the type of chemical reaction (and the predicted
chemical equation) that occurs when iron filings are added to 6M
hydrochloric acid.
Hypothesis: If Fe and HCl react, there will be a single displacement reaction,
resulting in the products H2 and FeCl2 because Fe is more reactive than H2.
Balanced Equation: Fe (s) + 2HCl (aq)  H2 (g) + FeCl2 (aq)
9. Design and Experiment – Propose an experiment to test your
hypothesis. If resources are available and you have your teacher’s
permission, perform the experiment.
The experiment that should be performed should be the same as the experiment
with Mg and HCl. They both give off H2 as a product, so if a flame is held over the
test tube, it should pop just like in the third experiment performed. This would
prove the reaction occured
Conclusion
Through examining the products and interactions that each compounds had on
each other in each of the experiments, the correct reaction type and equation
was achieved. This experiment proved that when Iron reacts with Copper Sulfate,
and Single Replacement action takes place, when Lead Nitrate reacts with
Potassium Iodide, a Double Replacement reaction takes place, when Magnesium
reacts with Hydrochloric acid, a Single Replacement reaction takes place, when
H2O2 is heated, a Decomposition reaction takes place, when NaHCO3 is heated,
a Decomposition reaction takes place, and when ethanol is heated, a
Combustion reaction takes. This lab directly relates to the lessons being learned
in class, such as how to complete different reaction equations, how to distinguish
between the types of reactions, how to determine if they exist (or if there is no
reaction), and how to balance the equation. Two possible sources of error that
could give the wrong results (a wrong reaction occurred or no reaction occurred)
are not enough heating or too little reactants. If there wasn’t enough heating,
then the reaction may not have occurred. If not enough of each reactant was
added, then the reaction that occurred might be so minimal that it could produce
no visual reactions (i.e. there may not be a “pop” of the flame).