CH 220: FINAL EXAM
78 Cards in this Set
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intermolecular forces
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attraction b/w molecules
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intramolecular forces
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attractions within a molecule
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dipole-dipole forces
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attraction b/w polar molecules
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London dispersion forces
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attractive forces caused by temporary or induced dipoles
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volatility
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tendency of a substance to become a gas
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hydrogen bonding
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IM attraction b/w H & O, N, or F; polar bond
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viscosity
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resistance to flow
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surface tension
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amt of work necessary to extend a liquid's surface
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steam
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water molecules above boiling pt
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vapor
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water molecules below boiling pt
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boiling point
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point where vapor pressure exeeds atmospheric pressure
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normal boiling pt
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boiling pt of a liquid at 1 atm (100° C H2O)
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enthalpy of vaporization (ΔHvap)
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energy needed to vaporize 1 mole of a liquid at 1 atm
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phase change
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transformation of one physical state to another
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endothermic
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energy put into a system (heating)
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exothermic
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energy released from a system (cooling)
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sublimination
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heating solid->gas
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deposition
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cooling gas->solid
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enthalpy of fusion (ΔHfus)
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energy needed to melt 1 mole of a solid
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triple point
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all 3 phases in equilibrium
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critical point
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highest T & P where you can achieve a liquid
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solution
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homogenous mixture of 2 or more substances
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strong electrolyte
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breaks apart fully
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colligative properties
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solution properties that depend on the # of solute particles, not the solute identity
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osmosis
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flow of solvent through semi-permeable membrane to equilize concentrations
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osmotic pressure
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max opposing pressure required to prevent osmosis from occuring
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electrolyte
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substance dissolved in water to produce charged particles (ions)
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Vant Hoff factor
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(i); # particles produced by an electrolyte
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acid
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substance that produces H+ when dissolved in water
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base
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substance that produces OH- when dissolved in water
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amphoteric
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any species that can react as either an acid or a base
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strong acid
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dissociates completely
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strong base
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completely dissociates in water (alkali metal hydroxides NaOH & alkaline earth hydroxides Ca(OH)2)
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buffer
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solution that resists change in pH when additional acid or base is added; composed of acid/base + its conjugate
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buffer capacity
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# of moles of strong acid/base needed to cause a 1 pH change of a buffer
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titration
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controlled mixing of 2 reactive species; monitor some function of the reaction
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acid-base titration
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plot pH as a function of added titrant
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equivalence point
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moles of acid present is equal to the moles of base added
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monoprotic
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donates 1 proton in an acid-base reaction
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polyprotic acid
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ability to donate more than 1 proton in an acid-base reaction (ex. amino acid)
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ligand
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atom or molecule capable of forming a covalent bond to a metal ion via an electron pair
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complex ion
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ion containing 2 or more ions or molecules that are stable themselves; ligand-metal combination
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monodentate ligand
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binds to a metal ion through only one site
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chelate
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ligand which binds a metal w/ at least 2 sites & forms a cyclic structure
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EDTA
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important chelating agent; 1:1 ratios
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direct titrations
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titrant added to metal ion solution until endpoint is reached & color change is observed
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back titration
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known excess of EDTA added to metal ion analyte; after reaction, remaining EDTA titrated with 2nd metal ion in a diff. reaction
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indirect titration
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EDTA titrant is used with and intermediary that has a known relationship w/ the analyte of interest
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endpoint
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point in titration at which there is a sudden change in a physical property (color, pH, conductivity, or absorbance); used as a measure of equivalence pt
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solubility equilibria
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equilibrium b/w solid & its dissolved constituents
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solubility
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max amt of solid that will dissolve in 1 L of pure water at 25°
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saturated
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when solution contains max amt of dissolved solution
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Le Chatelier's Principle
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If a system at equilibrium is disturbed, the direction in which it proceeds back to equilibrium is such that the disturbance is partly offset
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gravimetric analysis
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mass of a product determines quantity of analyte; dependent on precipitation
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classical/wet chemical analysis
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gravimetric & volumetric; tedious, slow, more accurate
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volumetric analysis
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volume of reagent needed to react with analytes determines amount of analyte
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instrumental analysis
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started w/ solid state electronics, fast, poor precision & accuracy
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oxidation
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loss of electrons; oxidation # increases
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reduction
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gain of electrons; oxidation # decreases
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oxidation numbers
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show how many electrons have been gained/lost by a neutral atom when it forms a compound
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electrochemistry
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studies relationship b/w chemical reactions & electricity
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electrochemical cell
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2 half cells; voltaic & electrolytic
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voltaic cell
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use chemical reactivity to generate electrical energy; spontaneous e- flow (i.e. battery); anode -, cathode +
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electrolytic cell
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use electrical energy to drive chemical reaction; not spontaneous (i.e. charger); anode +, cathode -
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cathode
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where reduction occurs
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anode
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where oxidation occurs
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salt bridge
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to preserve charger neutrality cations & anions move from a salt bridge to counterbalance moving e-
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spectrophotometry
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measurement of light intensity as a function of wavelength
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polarized light
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field oscillates in one plane
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normal light
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field oscillates in all directions
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blank
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contains all reagents except analyte, compensates for absorbance of pure solvent; generally subtract blank absorbance from all other absorbances before calculations
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isosbestic point
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wavelength where absorption spectra of 2 species cross each other; shows only 2 components present w/ a constant total concentration
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accuracy
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how close a measurement is to true value
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precision
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how well repeated measurements agree; reproducibility
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systemic error
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determinant error; bias, caused by incorrect procedure or faulty equipment; can be corrected
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random error
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indeterminant; resulting from intrinsic uncertainty of measurement; creates scatter in data; can be minimized but not corrected
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confidence interval
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range of values in which there is a specified probability that the "true" value will be found
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calibration curves
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plot of physical response against concentration
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CH 220: FINAL EXAM