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Physical Properties of OrganicCompounds

Review of Intermolecular Forces ofReview of Intermolecular Forces of

 Attraction (IFAs) Attraction (IFAs)1. London Dispersion Forces

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Review of Intermolecular Forces ofReview of Intermolecular Forces of

 Attraction (IFAs) Attraction (IFAs)2. Dipole-dipole Interaction

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Review of Intermolecular Forces ofReview of Intermolecular Forces of

 Attraction (IFAs) Attraction (IFAs)3. -!onding

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"elting Point and #oiling Point

#oiling Point - the temperature at which the

liquid form of compoundbecomes a gas (vaporizes)"elting Point - the temperature at which asolid is converted into aliquid

Factors Afecting Boiling and Melting Points

1. Polarity of Molecule

- higher polarity higher melting!boiling point

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$rends in #oling and "elting Points

Factors Afecting Boiling and Melting Points

1. Polarity of Molecule

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$rends in #oling and "elting Points

CH3   CH2   CH3   H2C CH CH3

Factors Afecting Boiling and Melting Points

1. Polarity of Molecule

HC C CH3

". Molecular #ize!$eight

- %ncrease M$& increase in boiling!meltingpoint'. ethanol n-pentanol n-heanol

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$rends in #oling and "elting Points

Factors Afecting Boiling and Melting Points

. *ranching

- %ncrease branching& decrease boiling!meltingpoint- eample+ n-pentane vs. neopentane

,. %ntramolecular -bonding

- presence of intramolecular -bondingdecreases boiling!melting point

- eample+ o-hydroy benzoic acid vs. p-hydroybenzoic acid

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$rends in #oling and "elting Points

Factors Afecting Boiling and Melting Points

. Molecular symmetry

- #ymmetrical molecules have lower boilingpoint and higher melting point as compared

to unsymmetrical molecules

ClCl   Cl

Cl

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- indicates how readily an electron cloud canbe distorted

$rends in #oling and "elting Points

Factors Afecting Boiling and Melting Points

/. Polarizability

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$rends in %olu!ility

Classication o Solvents

polar vs. nonpolar

protic vs. aprotic

Factors Afecting Solubility 1. 0ature of the #olute

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$rends in %olu!ility

Factors Afecting Solubility 

". arbon-chain length

- increase -chain length decrease watersolubility

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$rends in %olu!ility

Factors Afecting Solubility 

. *ranching

,. %ntramolecular -bonding

- n-butanol vs. tert-butyl alcohol

- Presence increases water solubility

- Presence decreases water solubility

- eample+ o-hydroy benzoic acid vs. p-hydroy

benzoic acid

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&'amples(