Types of Chemical Reactions
Students should wear safety glasses and protective clothing at all times when working in the lab.
All chemical reactions fit into one of five categories. These categories are combination,
decomposition, single replacement, double replacement, and combustion.
Combination reactions are reactions in which the elements are combined to form a single
compound. These reactions take the form A + B  AB.
Decomposition reactions are the exact opposite of combination reactions, as they have a
compound that falls apart into its component elements. These reactions have the general
formula AB  A + B.
When an element reacts with a compound to form a new element and a new compound, it
is said that there has been a single replacement reaction. This is because only one single
element has been replaced. These reactions can be expressed generally as
A + BC  AB + C.
If instead, two compounds are found in the reactants side of the equation, a double
replacement reaction will occur. The double replacement reaction can be expressed as
AB + CD  AD + CB. The parts of each compound are switched, leaving us with two
totally different compounds as products.
The final type of reaction is combustion, which occurs when your reactants are composed
only of carbon, hydrogen, and oxygen atoms. Every combustion reaction ends up making
only two products: carbon dioxide and water. This type of reaction can be expressed
CxHxOx  CO2 + H2O
Pre Lab Questions:
1. List the five types of chemical reactions:
2. List the reactants you need in part A, in part B, and in part C.
Procedure:
A. Copper Wire
1. Use the steel wool to clean a piece of copper wire until the wire is shiny.
Examine the wire and note its appearance.
2. Using crucible tongs, hold the wire in the hottest part of the burner flame
for 1-2 minutes. Examine the wire and note any change in its appearance
caused by the heat.
B. Hydrogen Peroxide
1. Pour a small quantity of hydrogen peroxide (H2O2) in a clean, dry test
tube. Note its appearance.
2. Add a small amount of catalyst (not involved in the reaction) iron (II)
nitrate, to the test tube and observe.
3. Insert a glowing splint into the top of the test tube to test for oxygen gas.
(The splint will burst into flame if oxygen is present)
4. Note any change in the appearance of the material in the test tube and note
the appearance of any residue on the side of the test tube.
C. Zinc
1. Stand a clean, dry test tube in a test tube rack. Add about 5 mL of 6 M
hydrochloric acid (HCl) to the tube. Carefully drop a small piece of zinc
metal into the acid in the test tube.
2. Using a test tube holder, invert a second test tube over the mouth of the
test tube in which the reaction is occurring. After about 30 seconds,
remove the inverted test tube and insert a burning wood splint into the
tube.
3. Record all your observations about the reaction, the products, and the
reactants.
Data: Fill in the table.
Reaction A
Reaction B
Reaction C
observation
of reactants
observation
of reaction
observation
of products
Questions:
1. The unbalanced equation for the reaction in part A is Cu + O2  CuO. What is
the balanced equation?
2. What type of reaction has happened in part A?
3. The equation for the reaction in part B is H2O2  H2 +O2. Write the balanced
equation below.
4. What type of reaction has happened in part B?
5. The equation for part C is HCl +Zn  ZnCl +H2. Write the balanced equation
below.
6. What type of reaction has happened in part C?