Chem123 Final Exam

open system

matter+energy can come in/out

closed system

only energy can go in/out

isolated system

nothing can go in or out

energy for an ideal gas

proportional to temperature

Graph when Pext is changing

curve

Graph when Pext is constant

rectangle

Intensive state variable

dont depend on system size

temp, density, pressure, molar mass, conc.,

Extensive state variable

depend on system size

volume, moles, mass, energy

important standard states

C_{(s, graphite)}

P_{4(s, white)}

S_{8(s, orthorhombic)}

Exergonic

∆G<0, spontaneous

Endergonic

∆G>0, non-spontaneous

Enthalpy at constant pressure

∆H = q

Zero-order half life

[A]₀/2k

half life gets shorter as reaction proceeds

First order half life

ln2/k

half life is constant

Second order half life

1/k[A]₀

half life gets longer as reaction proceeds

Group priority (nomenclature)

Carls - carbox. acid

Evil - ester

Aunt - amide

Nancy - nitrile (triple CN bond)

Always - aldehyde

Keeps - ketone

All - alcohol

The - thiol

Apples - amine

Hidden - hydrocarbon

Even - ether

Super - sulfide

Triple bond takes priority over double

Resonance patters

• double bonds follow +

• lone pairs follow +

• lone pairs follow double bonds

everyone chases +, + dont chase!

Electronegativity

sp³ < sp² < sp

Low → high electronegativity

• + prefer to be in sp³

• - prefer to be in sp

Newman Conformations

Eclipsed : Syn

Staggared: Gauche, Anti

Eclipsed, Syn

• 2 largest groups aligned

• highest energy

Staggered, Gauche

• largest groups are still closest to each other

Staggared, Anti

• 2 largest groups furthest away

• most stable

sigma bond rotation depends on 2 factors

1. bulkiness hinders rotation

2. low temp hinders rotation

finding the highest # of stereoisomers

least amount of symmetry + highest # of stereoceters

Properties of Enantiomers

Same:

• melting point

• boiling point

• density

• reactivity (achiral)

• solubility (achiral)

Different:

• taste

• odour

• interactions/reactivity (chiral)

• direction of rotation

Meso compounds

• has asymmetric centre but achiral

• are inactive

Nucleophile

takes the place of the leaving group

Electrophile

the main molecule that stays

SN2 rate

bimolecular

depends on electrophile and nucleophile

SN2 vs SN1

SN2:

• 1^º or 2^º carbons

• use polar aprotic solvent

SN1:

• 2^º or 3^º carbons

• use polar protic solvent

Leaving Group (factor that influence mechanims)

weaker bases = better leaving groups

F<Cl<Br<I

Nucleophile (factor that influence mechanims)

same row → more basic = reacts faster

same column → more polarizable = reacts faster

negatively charged > positively charged

less bulky = reacts faster

DOESNT MATTER FOR SN1

Polar aprotic solvent

No H available for H bonding

ex: acetone, DMSO, DMF, THF

Polar protic solvent

Has H available for H-Bonding (H bonded to N or O)

ex: H20, CH3OH, OH

pka = -9.5 vs pKa = -6.3

-9.5 is stronger than -6.3

Bomb calorimeter vs Coffee cup calorimeter

bomb calorimeter → constant volume

coffee cup → constant pressure