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Lab: Chemical Reactions
Introduction
Balancing Equations
The Law of Conservation of Matter says that matter can neither be created nor destroyed, but can be
changed in form. In other words, the total mass of the material(s) before the reaction is the same as the
total mass of material(s) after the reaction. Generally, this fact has been confirmed by countless
experiments. However, there is another way to understand this concept. You can think in terms of the
atoms themselves. Take the synthesis reaction between hydrogen gas and oxygen gas. The product of this
reaction is water. At this point it is helpful if your students understand the concept of diatomic molecules
i.e. H2, N2, O2, F2, Cl2, Br2, I2. The unbalanced chemical equation for this reaction is
H2 (g) + O2 (g) -----> H2O (l)
If you count up the number of hydrogen atoms on each side, then you find that each side has 2 hydrogen
atoms each. Now count up the oxygen atoms on each side of the chemical equation. The left side of the
equation has two oxygen atoms and the right side has only one.
2 atoms H + 2 atoms O -----> (equals) 2 atoms H + 1 atom O
This is obviously not equal. Now let's look at the balanced equation.
2H2 (g) + O2 (g) -----> 2H2O (l)
If you recount the number of atoms on each side for each substance, then you have
4 atoms H + 2 atoms O -----> (equals) 4 atoms of H and 2 atoms oxygen. Here both sides are equal.
To graphically illustrate:
H-H
H-O-H
+
H-H
O=O
----->
H-O-H
Therefore, it is the Law of Conservation of Matter that sets the ground rules that must be followed to
correctly balance chemical equations.
Types of Chemical Reactions
Background:
There are an infinite number of chemical reactions. Chemist have divided these into broad classifications
based on certain criteria. The most important classifications are; combination, decomposition, single
replacement, double replacement, combustion, acid-base and redox. Note that some reactions will fall
into more than one classification. For example, all single replacement reactions are also redox reactions.
Reactions are described with chemical equations. A chemical equation is the symbolic representation of
the chemicals involved in the reaction. These chemical equations can be used to describe both physical
processes and chemical reactions. All chemical equations consist of reactants, the starting materials,
products, the ending materials, the state of matter that the materials are in and a reaction arrow
representing that a reaction has occurred.
reactants
products
The states of matter are symbolized by subscripts which follow each chemical. The most common states
of matter are solid, liquid, gas and aqueous. The first three should be self-explanatory the final, aqueous,
occurs when a substance is dissolved in water. Gasses and ions are commonly found in an aqueous state.
The symbols are as follows; solid (s), liquid (l), gas (g) and aqueous (aq).
Here are two examples of chemical equations:
H2O(s)  H2O(l)
CH4(g) + O2(g)  CO2(g) + H2O(g)
The first is the physical process of ice melting the second is the combustion of methane gas. There is one
other aspect necessary in writing a proper chemical equation, the equation must have the same number of
each type atom on each side of the reaction arrow. The is the Law of Conservation of Matter, in other
words you are not allowed to create nor destroy matter. The first of the two above equations is fine, two
hydrogens on each side and one oxygen on each side. The second equation needs to be balanced. This
can be accomplished by placing a 2 in front of both the O2(g) and the H2O(g).
CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g)
On each side we find one carbon, four hydrogens and four oxygens. This equation obeys the conservation
of matter and is said to be balanced.
Occasionally you may see something written above or below the arrow. This is normally a catalyst,
platinum and nickel are a common metal catalysts. Another possibility is that the something is an
environmental necessity, for example, heat or ultra violet light.
Pt
2 CO(g) + O2(g)
2 CO2(g)

The above chemical equation occurs in an automobiles catalytic converter, converting carbon monoxide
into carbon dioxide in the presences of the a platinum catalyst. The platinum is the reason the catalytic
converter is expensive.
Combination reactions, two or more reactants combine to form one product. The general equation
is:
A+ BC
A specific example is the tarnishing of a silver tea set:
Ag(s) + O2(g)  Ag2O(s)
Several combination reactions can be observed:
 metal plus a nonmetal to produce a binary compound
 two nonmetals to produce a binary molecular compound
 metal oxide plus water to produce a metal hydroxide
 metal oxide plus CO2 to produce a metal carbonate
 metal oxide plus SO2 to produce a metal sulfite
 nonmetal oxide and water to produce an acid
Decomposition reactions, one reactant breaks to form two or more products. Decomposition reactions
are reversals of combination reactions. The general equation is:
A B + C
A specific example is the electrolysis of water, electricity is causes this reaction:
2 H2O(l)
V

2 H2(g) + O2(g)
Several decomposition reactions can be observed:
 decomposition of a binary compound to produce two elements
 decomposition of a tertiary compound
o metal carbonate produces a metal oxide and CO2
o metal sulfite produces a metal oxide and SO2
Single replacement reactions, one chemical replace another in a compound. The general equation is:
A + BX  B + AX
A specific example is zinc metal replacing iron in the iron(III) oxide compound, ships use this reaction to
keep their hulls from rusting.
3 Zn(s) + Fe2O3(s)  2 Fe(s) + 3 ZnO(s)
Metals can replace metals and hydrogen or nonmetals can replace nonmetals. The single displacements
reactions ability to take place is based on the activity series. An activity series is a list of metal in order
of their activities. In the case of a single displacement reaction hydrogen acts like a metal. A single
replacement reaction will only occur is the element reacting is more “active” than the element it is
replacing.
Double replacement reactions, chemicals in each of two compounds switch compounds. The general
equation is:
AB + CD  AD + CB
A specific example is allows for the removal of toxic barium from a water source by adding a compound
containing sulfate.
BaCl2(aq) + Na2SO4(aq)  BaSO4(s) + 2 NaCl(aq)
A double displacement reaction will occur only if one of the products of the reaction is:
 insoluble ionic compound
 insoluble gas
 weak acid or weak base
 water
A special type of double displacement reaction is the acid/base reaction. An acid/base reaction always
produces water and a salt.
Combustion Reactions: an organic compound reacts with oxygen to produce CO2 and water. An
organic compound will have carbon and hydrogen in its formula, and possibly oxygen. An element (not
Carbon) may also react with oxygen in a combustion reaction to produce an oxide, this is generally
considered a combination (synthesis) reaction.
Purpose
Execute and observe different types of chemical reactions, Qualitatively identify products of these
chemical reactions and write balanced chemical equations for these chemical reactions
Procedure
This lab is broken into stations, following are directions for each station. Pay particular attention to
disposal instructions.
This lab will use a flaming or smoldering piece of wood as a qualitative test for either CO2(g) or O2(g). If
the fire goes out, you have CO2 being generated, if the fire flames up, you have O2 being generated.
Station 1: Obtain a piece of magnesium ribbon. Holding it with forceps, ignite the ribbon on a Bunsen
burner flame. Do NOT look directly at the burning magnesium. Hold burning ribbon over wire plate so
that no burning magnesium lands on the lab bench.
Disposal: wipe ash into garbage can, clean bench area.
Word equation: magnesium reacts with oxygen to produce magnesium oxide.
Station 2: Place 10 drops of silver nitrate into a small test tube. Add 10 drops of sodium chloride to the
same test tube.
Disposal: flush content of test tube down drain, rinse test tube and return to beaker, clean bench area.
Word equation: aqueous silver nitrate reacts with aqueous sodium chloride to produce solid silver
chloride and aqueous sodium nitrate.
Station 3: Place a small amount of zinc into a test tube. Add enough dilute hydrochloric acid to just
cover the piece of zinc. Invert a test tube on top of reacting test tube. Wait 1 minute. Light a splint,
separate the two test tubes and insert the splint into the top test tube. Be Prepared!
Disposal: flush contents of test tube down drain, rinse test tube and return to beaker, clean bench area.
Word equation: zinc reacts with aqueous hydrochloric acid to produce aqueous zinc chloride and
hydrogen gas.
Station 4: Place a small scoop of sodium bicarbonate into a test tube. Add 3 mL of hydrochloric acid.
Invert another test tube on top. Light a splint, insert the lit splint into the bottom test tube, observe
results.
Disposal: Wash and dry test tube, clean station.
Word equation: solid sodium bicarbonate reacts with aqueous hydrochloric acid to produce carbon
dioxide gas, aqueous sodium chloride and water.
Station 5: Place 10 drops of potassium iodide into a small test tube. Add 10 drops of lead (II) sulfate to
the same test tube. Disposal: place test tube and contents into waste beaker.
Word equation: aqueous potassium iodide reacts with aqueous lead (II) sulfate to make aqueous
potassium sulfate and solid lead (II) iodide.
Station 6: Place 20 drops of hydrogen peroxide into a small test tube. Add a small amount of manganese
(IV) oxide to the test tube (just enough to cover the bottom of the test tube). HINT: Manganese (IV)
oxide is a catalyst. A catalyst is indicated by writing the formula for the catalyst over the arrow. Invert
another test tube on to the test tube containing the hydrogen peroxide and manganese (IV) oxide, Wait
about 2 minutes. Prepare a smoldering wood splint. Carefully insert the smoldering wood splint into the
bottom test tube.
Disposal: flush contents of beaker down drain, rinse test tube and return to beaker, clean bench area.
Word equation: aqueous hydrogen peroxide produces water and oxygen gas.
Complete attached data sheet and questions. Turn in lab data sheet ONLY. Ensure lab areas are clean
and organized.
Name:
Writing and Balancing Chemical Equations
Station
Reactants
Products
Type
Questions:
1. Name five types of chemical reactions.
2. What is a reactant in a chemical reaction? What is a product?
3. Name four signs of a chemical reaction.
4. What does the → mean in an equation?
Balanced Equation
5. Give the four symbols and descriptions of physical states of reactants and products.
6. Why must chemical equations be balanced?
Problems:
Balance the following equations
___ MnO2 + ___ HCl -----> ___ MnCl2 + ___ H2O + ___Cl2
___ Pb(NO3)2 + ___ K2CrO4 -----> ___PbCrO4 + ___KNO3
___ CO + ___ Fe2O3 -----> ___ Fe + ___ CO2
___ Zn(OH)2 + ___ H3PO4 -----> ___ Zn3(PO4)2 + ___ H2O
___ H2SO4 + ___ NaOH -----> ___ Na2SO4 + ___ H2O
___ Mg3N2 + ___ H2O -----> ___ Mg(OH)2 + ___ NH3
___ Si2H6 + ___ H2O -----> ___ Si(OH)4 + ___ H2
___ C2H6 + ___ Cl2 -----> ___ C2HCl5 + ___ HCl
Predict the products of the following reactions, identify the type of reaction, and balance the equation.
1)
__ Ag + __CuSO4 
Type:___________________________
2)
__ NaI + __ CaCl2 
Type:___________________________
3)
__ O2 + __ H2 
Type:___________________________
4)
__ HNO3 + __ Mn(OH)2 
Type:___________________________
5)
__ AgNO2 + __ BaSO4 
Type:___________________________
6)
__ HCN + __ CuSO4 
Type:___________________________
7)
__ H2O + __ AgI 
Type:___________________________
8)
__ HNO3 + __Fe(OH)3 
Type:___________________________
9)
__ LiBr + __ Co(SO3)2 
Type:___________________________
10)
__ LiNO3 + __Ag 
Type:___________________________