Articles
Ragsdale, Ronald O.; Zipp, Arden P. Helping students
to improve their approach to predicting the products of chemical reactions.
J. Chem. Educ. 1992 69 390.
Laboratory Experiments
Traditional
Web Based:
Some Web Sites
Lecture on September
25, 2000 Introduction to soluble ionic compounds, the solubility
table, ionic and net ionic equations.
Lecture on September
27, 2000 Double replacement reactions, neutralization reactions
and single replacement reactions and writing ionic and net ionic equations.
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Additional resources for chemical reactions.
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Pedagogy:
The first reaction my students see occurs on the second
day of class when I define a chemical reaction. The reactions I usually
do are;
Fe(s) + S8(s) ---> FeS(s)
Al(s) + Br2(l) ---> AlBr3(s)
(Actually Al2Br6(s))
I show these reactions from videodiscs and have the student
describe what they see. Initially all I'm trying to do is to demonstrate
chemical change. I usually describe these as formation/synethesis reactions.
To help me early on to lay the ground work for chemical
reactions my students begin to memorize several things;
the name and the symbols of the first 20 elements,
plus about thirteen additional common elements;
the formula for ALL of the elements in the periodic
table;
the phase of ALL of the elements in the periodic
table. This is the phase of every element at room temperature (25
degrees Celsius).
In the second chapter of most textbooks students must
earn nomenclature, learning monoatomic and polyatomic ions and very
simple differences between ionic and covalent compounds as determined
by the formula of the compound. So I discuss nomenclature of simple
binary ionic and binary covalent compounds.
Since they must learn how to write the formulas I discuss
how to use the periodic table to arrive at the most common oxidation
state for the monatomic cations and anions.
I have already told the students to memorize the first
20 elements in the periodic table and their formula, symbol and name,
and 20 additional common elements. Students are also told to memorize
the phase of every element in the periodic table. In the nomenclature
section they are also expected to memorize the common polyatomic anions
and common acids. I also work in the common bases and the first ten
alkanes.
So by the end of Chapter 2 of the text the students are
overwhelmed with a large amount of memorization, but they are also poised
to do a considerable amount of reaction chemistry.
Nomenclature of simple binary ionic compounds, symbol
and phase of the elements and the students are able to write an formation
reaction for binary ionic compound. I discuss the periodic table in
terms of the Group I-VIIIA elements. I talk about the magic nature of
the noble gas elements Group VIIIA. Groups IA elements like to lose
one electron to have a number of electrons equivalent to the nearest
noble gas. Group IIA like to lose two electrons, Group VIIA like to
gain electrons. The students are told the transition metals like to
lose two or three electrons.
Nomenclature for simple binary covalent compounds, symbol
and phase of the elements and students are prepared to write the formation
equation for several (not many) simple binary organic compounds. H2O,
CO2, CO, NO2, SO2, NH3.
Nomenclature for ionic compounds with polyatomic anions
and we are close to doing all the double replacement reactions. All
that is needed is the solubility table. That comes in by Chapter 4 or
5. I do not discuss double replacement reactions until I discuss the
nature of ionic compounds in water, solubility and the solubility table.
I always have a pair of laboratories that I have the
students do when IÕm covering this material. One is titled Conductivity,
and the other is titled Solubility.
Nomenclature of simple binary acids and ternary acids,
and simple ionic bases sets up neutralization reactions. While I cover
the nomenclature in chapter 2 I do not discuss neutralization reactions
until solution stoichiometry and titrations.
Since the students know the first ten alkanes they are
ready to handle combustion reaction for hydrocarbons. I add nitrogen
and sulfur containing hydrocarbons and discuss the the new products.
I also introduce alcohols and their combustion products.
Single replacement reactions I do by demonstrations,
Group I elements with water, Group II elements with hydrochloric acid.
This semester I do discuss single of the elemetnal form reacting with
a soluble metallic ionic salt. However, I did not discuss the activity
series this semester.
Can view these reactions by going to my Web Site and
entering CHEM1314 as the userid and avogadro as the password.
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Some comments about pedagogy as it relates to chemical reactions.
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