TYPES OF CHEMICAL REACTIONS
NICHOLAS DIPRETA
JONNY MASCI
DUE: 3/3/10
Pre lab: There are several types of chemical reactions and several methods to classify them.
One method is to classify them into four major types; Synthesis, decomposition (or analysis),
single replacement, and double replacement. Most reactions can be put into these categories.
In synthesis, two or more substances combine into a more complex one. A decomposition
reaction is the opposite e of a synthesis reaction, and a compound breaks down into two or
more substances. In a single replacement reaction, one substance is replaced by another more
active substance. In a double replacement reaction, the metal ions of two different compounds
replace one another. Most replacement reactions occur in aqueous solutions with free ions. In
a double replacement reaction, one product is a precipitate, an insoluble gas, or water. In this
investigation, students will be concerned with the molecular formulas and equations. In a
balanced equation, the number of atoms of any element must be equal on both sides of the
equation. Multiplying the coefficient and the subscript of an element give the same result on
both sides of the balanced equation. Students will observe examples of four types of chemical
reactions. Each will be expected to balance equations representing the observed reactions.
Purpose: The purpose of this experiment is to observe chemical reactions and identify the
reactants and products. Classifying the reactions and writing balanced equations are necessary.
Equipment
Lab burner, crucible tongs, microspatula, test tubes, test tube holder, test tube rack, wood
splints, sand paper, evaporating dish, safety ogles, lab apron or coat
Materials
Zinc, copper wire, magnesium ribbon, copper(II) carbonate, 6M Hydrochloric acid, 1M copper
(II) sulfate, 0.1 M zinc Acetate, 0.1 M sodium phosphate, 1M sodium sulfite
Safety
Burning magnesium makes a bright light, do not look at it or touch the flame. Never directly
smell a chemical, waft the gasses towards your nose. Pay special attention to the safety
symbols next to certain steps in the procedure. Wear safety goggles and protective clothing.
Procedure
Part A: Synthesis
1. Use fine sandpaper to clean a piece of copper wire until the wire is shiny. Note the
appearance of the wire.
2.Using crucible tongs, hold the wire in the hottest part of a burner flame for 1-2 minutes.
Examine the wire and not any change in its appearance caused by heating.
3. Place an evaporating dish near the base of the burner Examine a piece of magnesium
ribbon. Using crucible tongs, hold the sample in the burner flame until the magnesium starts to
burn. When the ribbon stops burning, put the remains in the evaporating dish.
Part B: Decomposition
4. Place 2 heaping microspatulas of copper (II) carbonate in a clean, dry, test tube. Note the
appearance of the sample.
5. Using a test tube holder, heat the CUCO3 strongly for about 3 minutes. Extinguish the flame
and then insert a burning wood splint into the test tube. If carbon dioxide gas is present, it will
put the flame out. Note the changes in the appearance of the residue in the test tube.
Part C: Single Replacement
6. Stand a clean, dry test tube in the test tube rack. Add about 5 mL of 6M hydrochloric acid to
the tube. Now carefully drop a small piece of Zinc metal into the acid in the test tube. Observe
and record what happens.
7. Using a test tube holder, invert a second test tube over the mouth of the test tube in which
the reaction is taking place. Remove the inverted tube after about 30 seconds and quickly
insert a burning wooden splint into the mouth of the tube. A pop indicates the presence of
hydrogen gas. Note the appearance of the substance in the reaction test tube.
8. Add about 5mL of 1M copper sulfate solution to a clean, dry test tube. Place a small amount
of zinc metal in the solution. Note the appearance of the solution and the zinc before and after
the reaction.
Part D: Double Replacement
9. Add about 2mL of 0.1M zinc acetate to a clean, dry test tube. Next, add about 2mL of 0.1 M
sodium phosphate tribasic solution to the test tube. Observe what happens and note anu
changes in the mixture.
10. Add about 5mL of 1M sodum sulfite solution to a clean, dry test tube. To this solution, add
about 1mL of 6M HCl. Note the odor given off by wafting some of the gas toward your nose.
Sample
Synthesis
Copper
Magnesium
Before Reaction
After Reaction
Shiny, thin strand
Shiny thin strand
Less shiny, broke apart
Less shiny, white, crumbly,
brittle
Decomposition
CuCo3
Before Rxn
Green powdery
After Rxn
Turns black, clumps together
Single Replacement
Zn+ HCl
Zn+ CuSO4
Before Rxn
Zn was grey, solution was clear
Blue solution, grey zinc
After Rxn
Solution bubbles a lot H2 produced
Zinc turns a darker color
Double Replacement
Zn(C2H3O2)+ Na3PO4
Na2SO3 + HCl
Before Rxn
Just two clear liquids alone
Just liquid and powder alone
After Rxn
Turns cloudy and opaque
Smells vinegar-like
Equations
Balance each of the equations by inserting the proper coefficients where needed. Write the
names of the reactants and products below the molecular equation for each reaction.
Synthesis
1. 2Cu (s) + 02 (g)  2 CuO(s)
Copper+oxygen copper oxide
2. 2Mg(s)+02 (g)  2MgO(s)
Magnesium+ Oxygen Magnesium oxide
Decomposition
3. CuCO3(s) CuO(s)+ CO2(g)
Copper Carbonate Copper Oxide + Carbon Dioxide
Single replacement
4. Zn (s)+HCl(aq) ZnCl2(aq)+ H2(g)
Zinc+ Hydrogen Chloride Zinc chloride+ hydrogen
5. Zn (s)+ CuSO4 (aq) ZnSO4(aq)+ Cu(s)
Zinc+ Copper Sulfate Zinc Sulfate+ Copper
Double Replacement
6. 3 Zn(C2H3O2)2 (aq) + 2 Na3PO4 6NaC2H302+ ZnPO4
Zinc Acetate+ Sodium Phosphate Sodium Acetate+ Zinc Phosphate
7. Na2SO3 (aq)+ 2HCl(aq) 2NaCl(aq) + H20(l)+ SO2 (g)
Sodium Sulfite+ Hydrogen Chloride Sodium Chloride+ water+ Sulfur Dioxide
Conclusions and Questions
1. In this experiment, what method was used to test for the presence of CO2 gas? What is
another test for CO2 gas? Write a balanced equation for this test.
The experiment that was used to test for the presence of C02 gas was the decomposition
reaction that was performed in part B(see procedure) of this experiment. The production
of quicklime (CaO) a chemical that has widespread use, from limestone by heating at about 850
°C also produces CO2:
CaCO3 → CaO + CO2
Calcium carbonate Calcium Oxide+ oxygen
2. What test was used to identify hydrogen gas? Write a balanced equation to represent this
test.
The single replacement reaction in part C(see procedure) in which Zinc was added to
hydrochloric acid produced hydrogen gas.
Zn (s)+HCl(aq) ZnCl2(aq)+ H2(g)
Zinc+ Hydrogen Chloride Zinc chloride+ hydrogen
3. Balance the equation below and identify the type of reaction represented by each
equation.
a. 2AgNO3 (aq)+ Cu (s) Cu( NO3)2(aq) + 2Ag(s) single replacement
b. BaCl2 (aq) + Na2SO4(aq) BaSO4 + 2NaCl(aq) double replacement
c. Cl2(g)+ 2NaBr(aq) 2NaCl(aq)+ Br2 single replacement
d. 2KClO32KCl(s)+ 302(g) decomposition reaction
e. AlCl3(aq)+3NH4OH(aq)  3NH4Cl(aq)+ Al (OH)3 (s) double replacement
f. 2H2(g)+ O2(g) 2H2O(g) synthesis