Chem 3Al Lab Exam Fall 2011

Front 1

size of atom and its polarizability are important when considering...

Back 1

acidity trends down a column of the periodic table

Front 2

more stable the anion...

Back 2

weaker base, stronger conjugate acid

Front 3

if acid form is stabilized by resonance...

Back 3

acid is weaker than comparable compounds

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Lewis acid

Back 4

molecule that can accept an electron pair

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Lewis base

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molecule that can donate a pair of electrons

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Loss of electrons is...

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oxidation

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gain of electrons is...

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reduction

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coulomb's law

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The attractive force between two oppositely charged objects is directly proportional to the product of the charge on each particle and inversely proportional to the square of the distance between them

Front 9

bond polarity is more important that molecular polarity when assessing...

Back 9

intermolecular forces between molecules

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intermolecular forces, van der Waals forces

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D-D, D-I-D, D-I-D-I (London dispersion) interactions

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ID-ID interactions (London Dispersion)

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An instantaneous dipole in one neutral atom or molecule induces a dipole in another atom of molecule (chain reaction); contributes to the differences in boiling point

Front 12

IDID interactions between linear alkanes...

Back 12

increase as the chain length increases

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boiling point

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temperature at which its vapor pressure = external pressure

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alpha

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polarizability: how easily the valence electrons are disturbed in the presence of a pole

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I

Back 15

isolation potential (energy to remove valence electrons)

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r

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distance between the atoms/molecules

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DD

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Interactions between two atoms or molecules with permanent dipoles; only force dependent on temperature

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u

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dipole moment = (size of charge) x (separation of charge)

Front 19

hydrogen bonding

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type of strong DD interaction between H and O/N/X --> "proton exchange": hydrogen moves from one delta - molecule to another

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DID

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Permanent bond dipoles in an atom or molecule induces dipoles in a neutral atom or molecule

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boiling point differences between alkanes and aldehydes

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ald (bond dipole moments) > alk (no bond dipole moments)

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soluble/non-volatile impurity effect on boiling point

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affects intermolecular forces and lowers the vapor pressure of liquid above solution --> boiling point of impure liquid increases

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reflux ring

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area above the solution where the vapor is in equilibrium with the pure liquid; temperature within reflects boiling point of liquid

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common recrystallization solvents

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water, ethanol, acetone, hexane, isopropanol, ethyl acetate

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activated carbon

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large/flat/porous molecule that has a non-polar surface and utilizes IDID and DID interactions to absorb molecules

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UV lamp (TLC)

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detects conjugated compounds (multiple bonds separated by a single bond)
non-conjugated compounds are inactive

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for TLC, stationary phase is ___ and mobile phase is ___

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solid, liquid

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the stronger the interaction between a component and the stationary phase...

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the slower the component is moved by the mobile phase

Front 29

adsorption chromatography using a polar stationary phase

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determine the rate at which individual components travel through the stationary phase

Front 30

partition chromatography

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The stationary phase is a thin film of liquid absorbed on the surface of an inert solid support; the mobiel phase is an immiscible liquid or gas

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normal-phase chromatography

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typical stationary phase is polar and the mobile phase is less polar than the stationary phase; therefore, polar compounds are more attracted to the stationary phase and are moved less by the mobile phase

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chromatography

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useful for separating mixtures of compounds and valuable for analysis, but DOES NOT determine if a substance is pure

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DNPH

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reacts with aldehydes and ketones, ketones take longer to appear

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NMR active

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must have a spin not equal to 0; 1H, 13C, 15N, 19F, and 31P have spin 1/2 (alpha & beta spin states)

Front 35

NMR - hydrogen attached to an sp2 hybridized carbon

Back 35

resonance generally at higher frequency