Monday, May 21, 2007

   Don't Mind this Chemistry Stuff.
Stoichiometry
“The basics of stoichiometry”

You can compare the amount on any substance in the same chemical equation using the formula weights and the coefficients of the materials in the equation.
**If you know the amount of one substance you can figure out the rest. **

GRAMS (molar mass) MOLES  (Avogadro’s number)  ATOMS

The molar mass is the mass of one mole of a substance and it is the same thing as the molar mass on the Periodic table. The molar mass is used as a conversion factor between grams and moles. Avogadro’s number is used as a conversion factor between moles and atoms.

Conversion factor between grams to moles
Ex. 25gHF==== > (25gHF) (1 mole HF) = 1.25 moles HF
(20g HF)

Conversion factor between moles to grams
Ex. 6.6 molesZnO==== > (6.6 moles ZnO) (81.39gZnO) = 537.1g ZnO
(1 moleZnO)

Conversion factor between moles to atoms
Ex. 2.50mol Zn====> (2.50molZn) (6.02*10²³atomsZn) = 1.51*10²4
(1 mol Zn)

Conversion factor between grams to atoms
Ex. 1.50gC====> (1.50gC) (1molC) (6.02*10²³atomsC) = 7.52*10²² atoms C
(12.01gC) (1molC)

Mass-mass problems use a different type of formula/concept to figure out the



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Chemical Nomenclature
“Nomenclature for dummies”

You first begin by identifying the element name on the Periodic table. The name of the metal is first, and the name of the non-metal has –ide added to the ending.

Ex. NaCl ====> sodium chloride

If a metal has more than one possible charge the Stock Method is written with roman numerals to indicate the ion using the charge.

Ex. FeF2 ===> iron (II) fluoride
FeF3 ===> iron (III) fluoride

For the Systematic Nomenclature, Greek prefixes are used to identify the number of atoms in an element.

Mono-1 di-2 tri-3 tetra-4 penta-5 hexa-6 hepta-7 octa-8 nona-9 deca-10

Ex. CO2 ====> carbon dioxide
N2O5 ====> dinitrogen pentoxide

Polyatomic compounds, known as oxyanions, are more difficult to name because depending on how many hydrogen atoms there are on the formula, that is how you determine if –ite or –ate is added to the end. –ite is added to compounds with one or two hydrogen atoms, but –ate is added to compounds with three or four hydrogen atoms.

Ex. NO2 ====> nitrite
NO3 ====> nitrate
SO3 ====> sulfite
SO4 ====> sulfate

There are two types of Acids; Hydro acids and Oxo acids. Hydro acids are written with –hydro in the beginning followed by the halogen/ element name and it ends with the letters –ic. Oxo acids are written with the polyatomic ion name first, followed by –ous or –ic, depending on how many hydrogen atoms the compound has. When there are more hydrogen atoms on a compound then –ic is used, but if there are less hydrogen atoms then –ous is used.

Hydro acids
Ex. HCl ====> hydrochloric acid
HF ====> hydrofluoric acid
Oxo acids
Ex. HNO3 ====> nitric acid
HNO2 ====> nitrous acid

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