ECU CHEM 1150 Test 3

Chemical Reaction

process in which one ro more substances are converted to one or more different ones

combustion reaction

substance reacts with o2. gas releasing heat

Balancing chemical equation with polyatomic ions

balance poly. ions as a unit; balance cations first, anions second

When balancing chemical equations what should you think the ratios as?

moles

General scheme for balancing equations

Mass A →(molar mass) Amount A (mol) → (molar ratio) Amount B (mol) →(molar mass) Mass B

Limiting Reactants

The reactant that makes the least amount of product - the other is in excess

Percent Yield

Actual yield/theoretical yield x 100%

Theoretical yield

the amount of product that may be produced

Actual yield

the amount of product that is made

Valence Bondy Theory

electrons reside in orbitals on individual atoms; the interaction energy is negative

Sigma bond

overlap along internuclear axis (end-to-end)

Pi Bond

side-by-side oberlap of 2 P orbitals

Hybridization

Mathematical procedure which the standard AO’s combined to form hybrid orbitals

Hybridization rules

# of standard AO’s = # of hybrid orbitals; e- probability density is more concentrated in a single directional lobe

2 e- groups, what is the e- and molecular geometries?

linear; linear

3 e- groups, what is the e- and molecular geometries?

Trigonal planer; w/one e- pair → bent

4 e- groups, what is the e- and molecular geometries?

tetrahedral; w/one e- pair→ trigonal pyramidal, w/two e- pairs → bent

5 e- groups, what is the e- and molecular geometries?

trigonal bipyrimidal; w/one e-pair → seesaw, w/two e- pairs → T-shaped [equatorial positions]

6 e- groups, what is the e- and molecular geometries?

octahedral; octahedral