Final Review CHGN 122 Flashcards Preview

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Flashcards in Final Review CHGN 122 Deck (53):
1

deltaG<0

Spontaneous process

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deltaG>0

Nonspontaneous process

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deltaG=0

reversible/ system at equilibrium

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solid->liquid

fusion, deltaS>0

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liquid->solid

freezing, deltaS<0

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liquid->gas

vaporization, deltaS>0

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gas->liquid

condensation, deltaS<0

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solid->gas

sublimation, deltaS>0

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gas->solid

deposition, deltaS<0

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favorable energy

favorable for energy in system to decrease, deltaH<0 is favorable

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favorable entropy

favorable for entropy of a system to increase, deltaS>0 is favorable

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diffusion

spread of one substance throughout another by unhindered random trajectories

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effusion

one-way leakage of a gas thru a pinhole

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IMF in decreasing strength

Hydrogen bonding, ion-dipole forces, dipole-dipole forces, London dispersion forces

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Hydrogen bonding

Hydrogen bonded to O, N, or F

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electronegativety trend

up and to the right more EN on Periodic table, F most EN

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EN bonds

A-A, C-H bonds are nonpolar A-B bonds polar, unless deltaEN>2 (then ionic)

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London Dispersion Forces (strongest to weakest)

ion induced dipole dipole induced dipole induced dipole induced dipole

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As strength of IMF increases:

BP increases MP increases viscosity increases (resistance to flow) Surface tension increases Vapor pressure decreases (less volatile)

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evaporation vs. vaporization

vaporization= liquid->gas, at BP evaporation= vaporization below BP at the surface of the liquid

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Vapor Pressure

equilibrium partial pressure of a substance

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Solid categories:

crystalline solids- regular, repeating lattice, most common Amorphous solids- lack long-range order on atomic scale

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Solid classifications:

ionic- ionic bonds (holds lattices together) metallic- metallic bonds covalent- covalent bonds and possibly IMF's

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Carbon structures

Diamond- 3-D covalent network Graphite- 2-D covalent network Graphene- single sheet of graphite Fullerenes- 'buckyballs' soccer ball shaped molecules Carbon Nanotubes- tubes of a single rolled sheet of graphite

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Mixture

homogeneous- uniform mixtures heterogeneous- Colloids- non-uniform, don't separate over time, smallish molecules Suspensions- non-uniform, separate over time, larger molecules than Colloids

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Colligative Properties

properties of solvents that change when a solute is dissolved in it, dependent on concentration: VP lowering MP depression BP elevation Osmosis

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Intermediate

a species produced in an early step of a multi step reaction and consumed in a later step, valley in a multi-step reaction profile

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Catalyst

a species consumed in an early stage and then regenerated in a later step; speeds up reaction by lowering energy of the rate determining step. homogeneous- same phase as reactants heterogeneous- different phase than reactants, usually a solid

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molecularity

number of molecule colliding during an element step

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elementary reaction

single-step reaction

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equilbrium

static dynamic- all chem rxn homogeneous- single phase heterogeneous- more than one phase *omit pure substance (l) & (s) b/c same concentrations throughout

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LeChatelier's Principle

when a system at equilibrium is stressed, there will be a net rxn to form a new equilibrium in the direction that reduces the stress Types of stress: changing temp adding or removing reactants/ products changing V at constant T of a gas

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Arrhenius Acid/ Base

Acid- produces an H+ Base- contains an OH-

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Bronsted-Lowry Acid/ Base

Acid- proton donor Base- proton aceptor

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Lewis Acid/ Base

Acid- electron pair accepter Base- electron pair donor

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Strong Acids

HClO4 (Perchloric Acid), HNO3 (Nitric Acid), HCl & HBr & HI, H2SO4 (Sulfuric Acid), H3O+ (Hydronium)

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Strong Bases

OH- (any soluble hydroxide; NaOH, KOH, Br(OH)2), NH2-,O2- (Oxide), H- (Hydride)

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Weak Acids

HF (Hydrofluoric Acid), NH4+ (Ammonium), and all others unless otherwise noted

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Weak Bases

NH3 (Ammonia)

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Conjugate Acid

add H+ to formula

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Conjugate Base

remove H+ from formula

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Buffer

an aqueous solution that contains significant amounts of both a WA and its conjugate WB, that resists pH change due to the common ion effect

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Oxidation

loss of electrons

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Reduction

gain of electrons

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LEOGER

Lose Electrons Oxidation, Gain Electrons Reduction

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Galvanic/ Voltaic Cell

operate in spontaneous direction, chemical energy to electrical energy... Batteries

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Electrolytic Cell

electrical energy to chemical energy; non-spontaneous, recharging battery, production of metals

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Standard Electrochemical Cell

25 degrees C, all aq. solns 1.0 M, all gasses 1 atm

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Ecell>0

spontaneous cell- Galvanic/ voltaic

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Ecell<0

non-spontaneous cell- Electrolytic Cell

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Anode

where oxidation occurs, electrons produced, anions migrate to anode, + (galvanic), - (electrolytic)

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Cathode

where reduction occurs, electrons consumed, cations migrate to cathode, - (galvanic), + (electrolytic)

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Rate Determining Step (RDS)

the slowest step in a multi-step mechanism that will decide the overall rate of the entire mechanism