January 31: HOMEWORK #1 HANDED OUT
- due on February 7, 2002 Ch.3.6-3.7: STOICHIOMETRY Works on MOLES only (not grams, liters, etc...) Needs a BALANCED reaction equation. Balanced reaction equations carry information about MOLAR
RATIOS of reactants and products. One can relate reactants to each other, products to each
other, as well as reactants to products.
Coefficients in front of compounds in a balanced reaction equation define
STOICHIOMETRIC EQUIVALENCES, eg. in an equation: 2
C2H6 + 7 O2
-> 4 CO2 +
6 H2O,
2 moles of C2H
6 are stoichiometrically equivalent to 7
moles of O2 as well as 7 moles of O2
are stoichiometrically equivalent to 6 moles
of H2O, etc...
One can produce
only as much of a product as the amount of the LIMITING REAGENT, (L.R.) allows
for.
L.R. always gets consumed first and runs out before the
other reactants can completely react. Always determine which of the
reactants is the limiting reagent, and base the amount of product(s) on the
amount of the limiting reagent. (The other reactant(s) is(are)
left in excess, ie. are not completely consumed)
THEORETICAL YIELD
ACTUAL YIELD
PERCENT YIELD (% yield)
January 29: Ch.2.7 continued.
Cations: Associate the charge of a simple monoatomic
metal cation with its placement in the periodic table. eg: sodium,
Na, is in the FIRST main group, it forms a +1 cation, etc... Combine your knowledge of the
names, formulas and charges of anions and cations to name ionic inorganic
compounds. Click here for 32 practice items
. Ch.3.1: Chemical Equations; balancing of equations. Read
text on margins of page 69 in BLB - very important! Ch.3.2: Types of chemical reactions, eg.: combustion in
oxygen (fancy phrase for burning), combination and decomposition reactions,
double replacement reactions, etc... Ch.3.3: Atomic and Molecular Weights:
recall how average atomic masses were calculated from isotopic masses (our
January 24 lecture, or read it on pages 74-76 in BLB). Ch.3.4 The mole: definition of a
mole, the Avogadro's number, NA; calculating of molar mass and
using molar mass to convert between moles and grams of substances, and moles
and numbers of "building blocks" Solve all the sample exercises and
practice problems from Ch.3.1-4, and the recommended questions from
BLB
. January 24: Ch.2 started:
Read through and understand the three laws: conservation
of mass, constant proportions and multiple proportions; Ch. 2.2-2.3: Atomic Structure: Sub-atomic particles (protons, neutrons and electrons)
and their charges and masses (amu); Mass Number, A and Atomic Number, Z;
know the difference and information each carries;Isotopes; Ch. 3.3: Calculation of average
atomic masses from abundances and isotopic masses; Ch. 2.4: The Periodic Table: there are trends in properties
of atoms (both chemical and physical) and a deep meaning behind the placement
of an element in the periodic table. Figs. 2.13, 2.18. Learn how to draw information
about elements from their location in the periodic table; Ch. 2.5-2.6: Empirical vs Molecular formula. Ch. 3.5: Empirical Formulas
from Analyses; Ch. 2.7: Naming Inorganic Compounds:
MEMORIZE
ACIDS, both their FORMULAS and NAMES
FIGURE OUT
the FORMULAS, CHARGES and NAMES of the anions which result from the ionization
of acids.
For each H atom in a formula of an acid, there will be
one negative charge in its anion, eg: HCl (hydrochloric acid) has
1 H atom, Cl- (chloride) has a -1
charge, H2SO4 (sulfur
ic acid) has 2 H atoms, SO42- (sulf
ate) has a -2 charge, H3PO3 (phosphor
ous acid) has 3 H atoms, PO33- (phosph
ite) has a -3 charge, etc... January 22: Introduction; Hand-outs: course syllabus and write-up on cross proportions; Use any method of solving problems that works for
you. Possibly give the cross-proportions a
chance! Significant figures for additions and subtractions as
well as multiplications and divisions. Note, there are differences in approach.
Need a check for (in)sanity? Check this web site:
http://www.essbasetools.com/instest.htm
. My ex-students from the GWN (great white north) sent this one to me.
