Investigating Chemical Reactions using the Molecular Model Kits
Directions: use the information below to complete the individual worksheet, then build the
required reactions and complete the GoogleClass document for your group.
PART 1: use ipad, molecule kit, and worksheet
Background Information:
Chemical reactions occur when molecules combine to form new substances. In order to do
this, the bonds between the atoms in the starting molecules must be broken and new bonds are
formed between the newly rearranged atoms in the ending molecules. The breaking of these
bonds requires energy and the forming of new bonds releases energy. The properties of the new
substance(s) are different than the properties of the original molecules involved in the reaction.
Other indicators that a chemical reaction has taken place are: formation of a precipitate (solid
formed from mixing two solutions), temperature change, color change, formation of a gas (odor).
The reaction can be described using the chemical formulas for the molecules involved and
a chemical equation format illustrated here. reactant + reactant  product + product
There can be one or more reactants and one or more products in the reaction.
The elements that make up the molecules in the reactants MUST be present in the
molecules in the products. In other words, no new elements can appear in the products that were
not in the reactants. Once all of the chemical formulas are correctly written, the equation must be
balanced. This means that with same number of each type of element must be on each side.
Why balance? http://www.chemteam.info/Equations/Balance-Equation.html
Coefficients (numbers in front of chemical formulas) may be added to the equation to
make more of a specific element, but you may NEVER CHANGE SUBSCRIPTS once the formulas
are correctly written (see example below, notice there are six carbons, 12 hydrogens, and 18
oxygens on each side of the arrow).
C6H12O6 + 6 O2  6 H2O + 6 CO2
Balancing equations explained: https://www.khanacademy.org/science/chemistry/chemicalreactions-stoichiome/balancing-chemical-equations/v/balancing-chemical-equationsintroduction
Certain elements, when written by themselves in a chemical equation, always have a
subscript of 2. These seven elements are Br, I, N, Cl, H, O, F (notice the O2 molecule by itself on the
left side in the above example). The different types of chemical reactions used in this lab are
SYNTHESIS, DECOMPOSITION, COMBUSTION, SINGLE REPLACEMENT, AND DOUBLE
REPLACEMENT. FYI- the Latin prefixes: di = 2, tri = 3, tetra = 4
Types of reactions explained:
http://www.asd5.org/cms/lib4/WA01001311/Centricity/Domain/638/Five%20Types%20of%
20Chemica%20Reactions.pdf
PART 2: use ipad, molecule kit, and GoogleClass doc
For each type of chemical reaction, do the following:
a) identify the type of reaction
b) write a balanced chemical equation
c) build and take a picture of the reactants and products
d) using the table below, calculate the total energy absorbed (by the reactants) and released
(by the products) by adding up the individual energies for each bond.
Bond
Energy (kJ/mol)
Bond
Energy (kJ/mol)
H–H
436
C–C
347
O–H
464
C=C
607
C–H
413
CΞC
839
C–O
360
C=O
805
N–H
393
O=O
498
O – Cl
205
C-F
488
C – Cl
330
I–I
151
O–I
201
Cl – Cl
243
OΞC
351
F–F
153
NΞN
945
H – Cl
432
Na – Cl
787
Na – OH
900
EXAMPLE: C2H4 + 3 O2  2 CO2 + 2 H2O
reactants
C-H 4(413)= 1652 KJ
C=C 1(607)= 607 KJ
O=O 3(498)= 1494 KJ
total = 3753 KJ
Combustion
products
C=O 4(805)= 3220 KJ
H-O 4(464)= 1856 KJ
total = 5076 KJ