Types of Chemical Reactions
Purpose:
To observe chemical reactions in order to determine the reaction type. To write balanced
chemical equations for each reaction.
Background:
In this experiment, you will learn to differentiate among five general types of chemical reactions.
You will carry out certain representative reactions. From your observations you will attempt to
identify the products of each reaction and to determine the type of reaction that has taken place.
The types of reaction you will consider are the following: combination reactions, decomposition
reactions, single-replacement reactions, double-replacement reactions, and combustion reactions.
The majority of common chemical reactions can be classified as belonging to one of these
categories. A brief description of each reaction type is provided below.
Combination reactions are reactions in which two or more substances combine to form a
single product. The reactants may be elements or compounds, but the product is always a single
compound. As example of a combination reaction is the reaction of sulfur trioxide and water to
form sulfuric acid.
SO3(g) + H2O(l)

H2SO4(aq)
Decomposition reactions are reactions in which a single substance breaks down into one
or more simpler substances. There is always just a single reactant in a decomposition reaction.
An example of a decomposition reaction is the breakdown of calcium carbonate upon heating.
CaCO3(s) + heat

CaO(s) + CO2(g)
Single-replacement reactions are reactions in which an element within a compound is
displaced by a separate element. This type of reaction always has two reactants: an ionic
compound and an element. An example of a single-replacement reaction is the reaction of zinc
metal with hydrochloric acid.
Zn(s) + 2 HCl(aq)  ZnCl2(aq) + H2(g)
Double-replacement reactions are reactions in which a positive ion from one ionic
compound exchanges with the positive ion of another ionic compound. These reactions typically
occur in aqueous solution and result in either the formation of a precipitate, the production of a
gas, or the formation of a molecular compound such as water. As example of a doublereplacement reaction is the reaction that occurs between aqueous silver nitrate and aqueous
sodium chloride. A precipitate of solid silver chloride is formed in this reaction.
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
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Combustion reactions are reactions in which an element or compound reacts rapidly with
oxygen gas to liberate heat and light energy. Commonly, the compounds combining with oxygen
in these reactions are hydrocarbons, compounds consisting wholly of hydrogen and carbon. The
well-known combustible fuels kerosine and gasoline, for instance, are hydrocarbon mixtures.
The complete combustion of a hydrocarbon yields carbon dioxide and water as the reaction
products. If insufficient oxygen is available, combustion will not be complete and carbon
monoxide and elemental carbon may be obtained as additional products of the reaction. An
example of a combustion reaction is the burning of methane gas to give water (in the form of
steam), carbon dioxide, heat, and light.
CH4(g) + 2 O2(g)

CO2(g) + 2 H2O(g) + heat + light
You will be producing three gases in this experiment. Each gas can be detected using different
means. Hydrogen gas can be detected by placing a burning wood splint at the mouth of the test
tube. A small flame and noise will be produced in the test tube. Oxygen gas can be detected by
holding a glowing wood splint in the test tube. If the splint re-ignites or glows brighter it
indicates the presence of oxygen. Carbon dioxide gas can be detected by holding a burning
wood splint in the test tube. The wood splint will be extinguished in the presence of carbon
dioxide.
Equipment:
Safety goggles (to be worn at all times during the experiment)
Medium test tubes
Wood splints
Bunsen burner
Scoopula
Test tube holder
Test tube clamp
Ring stand
Dropper
Crucible tongs
Watch glass
Evaporating dish
Test tube stand
10-mL Graduated cylinder
Wash bottle with distilled water
Chemicals:
Iron filings, Fe
0.1 M Potassium iodide, KI
Copper(II) sulfate pentahydrate, CuSO45H2O
3% Hydrogen peroxide, H2O2
Magnesium turnings, Mg
1 M Hydrochloric acid, HCl
0.1 M Lead(II) nitrate, Pb(NO3)2
Solid Potassium iodide, KI
Alka-seltzer tablet, sodium bicarbonate/citric acid, NaHCO3/H3C6H5O7
Procedure:
As you perform the experiment, record your observation on your report sheet.
1. Iron metal and copper(II) sulfate solution. Place 5 mL of copper(II) sulfate solution into a
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test tube. Add one scoop of iron filings to the test tube. Observe the reaction after 10 minutes.
Pour the solution into the copper sulfate waste container and place the solid on a clean watch
glass. Write down your observations of the solid. Place the solid on a piece of paper towel and
dispose in the trash.
2. Lead(II) nitrate and potassium iodide solutions. Place 20 drops of potassium iodide
solution into a test tube. Add 5 drops of lead(II) nitrate solution. Record your observations.
When complete filter the solution.
3. Action of heat on copper(II) sulfate crystals. Put two small crystals of copper(II) sulfate
pentahydrate into a dry test tube. Fasten a utility clamp to the upper end of the test tube and
clamp onto a ring stand. Hold the tube by the clamp so that it is almost parallel to the surface of
the lab table. CAUTION: Do not point the open mouth of the test tube at yourself or
anyone else. Make observations as you gently heat the crystals in a burner flame for
approximately 30 seconds. Heat only the bottom of the tube where the crystals are located.
Record your observations. When the test tube is cool add a few drops of water to the crystals.
Record your observations. Discard the crystals in the copper waste container provided in the
back of the room.
4. Magnesium metal and hydrochloric acid. Place 5 mL of 1 M hydrochloric acid into a test
tube. CAUTION: Hydrochloric acid is corrosive. Place the test tube in a test tube rack. Put 2
to 3 pieces of magnesium metal into the acid solution. Hold an inverted dry test tube over the
reaction test tube and collect the gas being produced. Test for the presence of gas by holding a
burning wood splint at the mouth of the inverted test tube after the gas has been collected.
Record your observations. Discard the solution in the sink and wash the test tube.
5. Action of a catalyst on warm hydrogen peroxide. Place 2 mL of 3% hydrogen peroxide
solution into a medium test tube. Use a utility clamp to secure the test tube to a ring stand.
CAUTION: Make sure that the mouth of the test tube is pointed away from you or anyone
else. Heat the solution very gently until it is warm. Turn off the burner and add a “pinch” of
solid potassium iodide to the solution and immediately check for the production of gas by
holding a “glowing” wood splint into the mouth of the test tube. Dispose of the solution in the
sink and wash the test tube.
6. Alka-seltzer in water. Place 5 mL of water into a large test tube. Add a “scoop” of crushed
alka-seltzer to the water and immediately check for the production of gas by inserting a burning
wood splint into the mouth of the test tube. Record your observations. Dispose of the solution in
the sink and clean your test tube.
7. Magnesium ribbon and oxygen. Obtain a strip of magnesium ribbon. Place your
evaporating dish close to the Bunsen burner. Hold the end of the ribbon with a crucible tongs.
Hold the magnesium in the burner flame until it ignites and then hold it over the dish.
CAUTION: Do not look directly into the bright flame of the burning magnesium. Observe
the remains of the magnesium. Record your observations and clean the evaporating dish.
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